Even Flash Can Get Viruses

Mechel Conrad writes: "Heise Online(German) writes about a Virus called SWF/LFM-926. It consists of a Macromedia Flash movie and seems to be the first of its kind. It uses Flash's scripting language in order to open a debug terminal creating and executing a file called V.COM, which infests other .SWF Files. Although the virus is not very dangerous and not widespread yet, it suggests clear security holes in Flash." The translation of the Heise article is quite readable, too. Update: 01/08 22:47 GMT by T : bdavenport adds: "this report on Yahoo lists a new Shockwave virus as low grade due to the need of manual downloading. infoworld is reporting that McAfee has upgraded to high risk after several Fortune 500 firms have reported it in the wild, arriving as an email attachment."

Comments

McAfee

[hogsback]

McAfee information is here

Looks like it isn't very likely to succeed - it needs Windows NT and the stand alone version of the flash player.

Just proof of concept really.

Build it, and they will...

[Ethelred Unraed]

...write a virus for it.

Cheers,

Ethelred

Many scanners don't scan .swf files

[geirt]

Many virus scanners don't scan .swf file by default, so you have update your virus signature file (which is automatic on most scanners) and reconfigure your scanner to scan .swf files (unless you already scan all files on your computer).

This means that if advanced .swf viruses are created, they could become a real problem until system admins wakes up and gets a clue (and that takes a loooong time, look at Code Red)

Infoworld is reporting on a *different virus*

[philam3nt]

It appears that the articles have not been read carefully. After comparing the the three, there are two Flash virii being spread around.

Virus 1 (Conrad's submission) - SWF/LFM.926
The virus, dubbed SWF/LFM.926...must be downloaded manually and cannot spread...over e-mail. (Yahoo)
...and after being run, infects other Flash movies while displaying the message "Loading Flash-Movie...". The virus exploits the scriptability of Macromedia Flash to generate a file V.COM, which gets executed afterwards without confirmation. (German trans. - thanks entrox!!)

Virus 2 (bdavenport's infoworld submission) - Creative.exe
The virus...arrives in an e-mail bearing the subject line, "A great shockwave flash movie."
The worm, which first appeared Thursday, is delivered to users in the form of an e-mail attachment that appears to be a Shockwave Media Player. When a user tries to view the movie attachment, the worm sends a copy of itself to all people in the address book of the user's Microsoft Outlook e-mail program, potentially clogging e-mail networks.
One reason the Creative.exe virus may be spreading so quickly is that it uses the Shockwave Flash movie icon. (Infoworld)
...but if you check the date of the Infoworld article, it's December 1, 2000.

From Symantec:
Discovered on: November 30, 2000
Due to a recent decrease in world-wide infections of this worm, SARC has decreased the threat level of this worm to 3 and removed it from the Top Threats list.

W32.Prolin.Worm uses Microsoft Outlook to email a copy of itself to everyone in the Outlook address book. The worm moves all .mp3, .jpg, and .zip files to the root folder. It renames each of these files and appends the following text to the extension of each file:

change atleast now to LINUX

Also Known As: TROJ_SHOCKWAVE.A, CREATIVE, TROJ_PROLIN.A

So...Creative.exe is NOT a flash virus, and is old news, unrelated to SWF/LFM-926.

That vulnerability is purely theoretical...

[chazR]

The still-excellent l0pht once informed the world that Microsoft had a serious security problem in a product.MS responded with the famous "That vulnerability is purely theoretical.". So, l0pht released a real exploit for the vulnerability.

Apologies, it's hard to find the original links since l0pht got up in the morning, put on a suit, and became @stake

Hello. Wake up. Theoretical vulnerabilites become real, nasty, exploited vulnerabilites very fast. I assume you read comp.risks?

Looks like it isn't very likely to succeed

LOOKS LIKE? It's a done deal. Somebody has exploited a widely-distribited scripting engine. The people who did it as a "proof-of-concept" have proven that the interpreter for this language is wide-open and gagging for a jolly good rogering. I wonder how many unchecked buffers there are in that code. I wonder how it handles multi-byte characters. I desperately hope it wasn't written in C.

I sit here as a smug old Unix hacker, secure in the knowledge that lisp and Smalltalk programs are unlikely to be attacked in the same way that C programs are.

I'm also sure I'm wrong.

No vulnerability in Flash itself

[silhouette]

The reason the stand-alone Flash virus file is able to access CMD.EXE has nothing to do with any inherent security hole in the basic Flash player itself. The stand-alone file uses a fairly well known (in the Flash community) function that is only available in the stand-alone Flash player. In fact, Macromedia even has this function documented in their Flash support section. It's the "exec" command that takes an argument of the path to an application to execute.

This virus really has more to do with running an unknown executable than it does exploiting some kind of vulnerability in Flash. This is because any stand-alone Flash player file is an .exe, not a .swf. The stand-alone .exe is composed of 1) The .swf file that runs and 2) The entire Flash player itself (~2megs) in executable form. By including the entire player within the file, the bundled .swf can be run anywhere without any necessary previous installation.

What cracks me up personally is that the very possibility of a Flash virus has been discussed before on Flash community developer message boards. When the "exec" command for the stand-alone player was still undocumented and somebody posted about it (having "discovered" it somehow) there was quite a discussion about the new functionality uses. But, there was also some speculation on how it could be used for malicious purposes. This was around a year ago, IIRC.