Did a search on all logs for January. Found 337 hits, all HQX files. All but 2 were viruses, and those 2 had suspicious looking from addresses and I am assuming were unviable corrupt versions of viruses.

 

John T

eServices For You

 

"Seek, and ye shall find!"

 

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Markus Gufler
Sent:
Wednesday, February 01, 2006 6:40 AM
To: Declude.Virus@declude.com
Subject: RE: [Declude.Virus] Encoded viruses...worried

 

I've grep'ed trough the logfiles for the last 7 days on my servers

 

2981 lines has sources of "\.BHX|\.HQX|\.B64|\.UU|\.MIM|\.MME" (ignoring double counts for the second av scanner)

 

After filtering out all lines containing "Kapser" and "Mywife" there remains the following 4 lines

 

01/25/2006 11:46:45.937 q570b9f4500e492b1.smd Found file with mismatched extensions [Attachments001.BHX-Removed Attachment.txt]; assuming .exe
01/26/2006 08:07:23.078 q7525030700d4d05a.smd Found file with mismatched extensions [Attachments00.HQX-Removed Attachment.txt]; assuming .exe
01/26/2006 08:08:23.890 q755303060132d08f.smd Found file with mismatched extensions [Attachments001.BHX-Removed Attachment.txt]; assuming .exe
01/27/2006 21:51:19.375 q87bd58b10020b63d.smd Warning: EOF in middle of MIME segment [] [------=_NextPart_001_0008_01C6238B.B6472520]

 

This looks very promising that declude is already handling it in order to catch malicious code inside such attachments.

Note: the 4.th line is listed due the "MIME"

 

Markus

 

 

 

 


From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Matt
Sent: Wednesday, February 01, 2006 3:19 PM
To: Declude.Virus@declude.com
Subject: Re: [Declude.Virus] Encoded viruses...worried

You know, I was going to ask if you would do a search, but I figured you might do it anyway :)  You did leave out the ".uue" extension, but I doubt that would have changed your results.

I suppose that if these extensions aren't hardly ever used anymore, it might be prudent enough to just watch for the possibility of the tactic to become widespread and then take action.

I do have a fair number of Mac users and probably more overseas traffic that you do, so I think that I am going to have to search a little on my own.  Unfortunately I zip all of my logs nightly, so it isn't practical to search through all of them.

Matt



Colbeck, Andrew wrote:

On the plus side, there are mitigating circumstances...

 

First, let me point out that although the antivirus companies will lag behind the virus authors, the antivirus guys aren't sleeping.

 

For many years, the bad guys have been using encoding methods and 3rd party applications to obfusticate their software as a cheaper alternative on their time than writing polymorphic code whose very technique gave them away.

 

PKLite was probably the first 3rd party tool used.  I've recently seen PAK, UPX and FSG... all three of which were caught by F-Prot because the antivirus guys simply make signatures for the binary itself, and don't bother including unpacking methods for all possible compression/encryption methods.  This explains why we have relatively few upgrades on the engines themselves.

 

The F-Prot documentation mentions (I think) only zip decoding, but we know that it certainly does UPX and RAR decoding based on issues that have been raised with each (for the former, pathetic speed and the former, a buffer overflow).

 

If you want to see what your virMMDD.log might reveal about this latest malware this month and what attachments you're seeing anyway, try this:

 

egrep "\.BHX|\.HQX|\.B64|\.UU|\.MIM|\.MME" vir01??.log

 

(if you don't want the filename, stick a -h parameter and a space before that first quotation mark)

 

By doing this, against my virMMDD.log I just discovered that F-Prot decodes BHX and HQX attachments too.

 

By doing something similar against my nightly virus-scan-the-spam-folder logs I also discovered that I have zero non-viral messages using the unconventional attachment formats in the last two months.  You can take that as an indication that it's okay to ban those formats if you wish, but I'll warn that I have a pretty homogeneous Windows user base.

 

.... and that's a wrap for tonight.

 

Andrew 8)

 

 

 


From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Colbeck, Andrew
Sent:
Tuesday, January 31, 2006 6:04 PM
To: Declude.Virus@declude.com
Subject: RE: [Declude.Virus] Encoded viruses...worried

John, the other formats are common (or, were common) on Macintosh and Unix based systems for binary attachments and for attached messages.  Eudora for Windows used to expose several of these formats for message construction.

 

They've fallen into disuse in favour of MIME attachments, but they are still extant.

 

Blocking messages containing those attachment formats may be reasonable for you if you're doing postmaster alerts and can check whether you've found false positives.

 

Like Matt, I'm somewhat worried that this technique will become as common a nuisance as encrypted zips.  Until recently, I've put my faith in the combination of Declude unpacking the attachments (I've assumed MIME encoding only) and F-Prot's packed and server options to otherwise do message decoding before virus scanning.

 

I've been watching for copies of Blackworm that might be caught on my system so that I check if Declude+F-Prot would catch these other packing formats, but no luck so far (or rather, I've had the good luck to receive so few copies in so few formats).

 

Andrew 8)

 

 


From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of John T (Lists)
Sent:
Tuesday, January 31, 2006 5:44 PM
To: Declude.Virus@declude.com
Subject: RE: [Declude.Virus] Encoded viruses...worried

Actually, I am already blocking hqz and uue so I went and added the others and will see what happens.

 

John T

eServices For You

 

"Seek, and ye shall find!"

 

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of John T (Lists)
Sent:
Tuesday, January 31, 2006 5:37 PM
To: Declude.Virus@declude.com
Subject: RE: [Declude.Virus] Encoded viruses...worried

 

Matt, are you saying the attachment as Declude would see it is B64, UU, UUE, MIM, MME, BHX and HQX? If that is so, what harm would be in blocking those for now?

 

John T

eServices For You

 

"Seek, and ye shall find!"

 

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Matt
Sent:
Tuesday, January 31, 2006 4:50 PM
To: Declude.Virus@declude.com
Subject: [Declude.Virus] Encoded viruses...worried

 

Someone just reported to me that MyWife.d (McAfee)/Kapser.A (F-Prot)/Blackmal.E (Symantec)/etc., has a 3rd of the month payload that will overwrite a bunch of files.  It's really nasty.  More can be found at these links:

    http://isc.sans.org/diary.php?storyid=1067
    http://vil.nai.com/vil/content/v_138027.htm

This started hitting my system on the 17th, possibly seeded through Yahoo! Groups.  The problem is that it often sent encoded attachments in BinHex (BHX, HQX), Base64 (B64), Uuencode (UU, UUE), and MIME (MIM, MME), and I'm not sure that Declude is decoding all of these to see what is inside.  For instance, I found that some BHX files that clearly contained an executable payload, showed up in my Virus logs like so:

01/16/2006 05:36:49 Q7741EFB6011C4F95 MIME file: [text/html][7bit; Length=1953 Checksum=154023]
01/16/2006 05:36:50 Q7741EFB6011C4F95 MIME file: Attachments001.BHX [base64; Length=134042 Checksum=8624521]

There was no mention about the payload inside of it, and there almost definitely was.  The same attachment name with the same length was repeatedly detected as a virus later on that day.  This likely was a PIF file inside, though it could also have been a JPG according the notes on this virus.  I, like most of us here, don't allow PIF's to be sent through our system, but when the PIF is encoded in at least BinHex format, it gets past this type of protection.

Here's the conundrum.  This mechanism could be exploited just like the Zip files were by the Sober writers and continually seeded, but instead of requiring some of us to at least temporarily block Zips with executables inside, an outbreak of continually seeded variants with executables within one of these standard encoding mechanisms would cause us to have to block all such encodings.  I therefore think it would be prudent for Declude to support banned extensions within any of these encoding mechanisms if it doesn't already.  I readily admit that this could be a lot of work, but it could be very bad if this mechanism becomes more common.  This particular virus is so destructive that a single copy could cause severe damage to one's enterprise.  I cross my fingers hoping that none of this would be necessary, but that's not enough to be safe.

Matt

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