Info on Worm.ExploreZip: I'm in the process of cleanup - my day job employer got hit, and we're NT with no 95/98 to speak of. Here are some interesting tidbits that I haven't seen on some of the commercial Anti-Virus web sites regarding NT. Payload: - The trojan can come into any email client, obviously. If executed, it will proceed to go active in memory. In other words, you do not need Outlook for the Payload to activate, just a Win32 machine. A Notes mail client user probably did the most damage in our environment to network NT file servers. - It will have a process running called _setup.exe, zipped_f.exe, and possibly explore.exe. - One of our users reported seeing explore.exe running as an application, although I wasn't able to confirm this. - It deletes files with *.h, *.c, *.cpp, *.asm, *.doc, *.xls, and *.ppt extensions on all drives (C through Z) that are currently mapped. - Every few minutes it will repeat the deletion process. This is particularly nasty if you are trying to do restores to network drives while the virus is still active in your environment. Progation: - On the Melissa-style method of propagation, it checks the user's Inbox in Outlook. The Outlook client does not have to be running, as the trojan uses MAPI calls. - Propagation is triggered by the arrival of a new message into the Outlook's Inbox. - Once triggered, the virus takes the first two names in the header and uses it to plug into the text of the message. If more than one user name is in the message header (possible if you are using distribution lists or role-based mail boxes that forward mail to multiple people) it is possible the names will not be in the correct order. Also if you use Lastname, Firstname as a naming convention you will get Lastname, plugged into the messages. - It creates the message with the names and attaches the trojan, naming it zipped_files.exe with the happy message as reported on most Anti-Virus vendor sites. - In other words, you send an email to billgat_private with a subject of Microsoft Sucks, he's infected and his machine is up and running, you will get a reply with a subject of Re: Microsoft Sucks with the attachment. I mean he says he'll get back with you and to read the attached zipped docs, and you being Joe/Josey corporate user check it out. False message saying it's a corrupt zip, blah, blah, blah, and now you're sending out trojans. We got hit when email was sent to some engineers at Microsoft, and the reply came back with the trojan. The nature of the email sent to Microsoft was "where is the info we requested" so it seemed natural that the attachment was supposed to be a self-extracting zip. That's right, Microsoft got hit, so I would guess a few source code files and Office docs were wiped. Hopefully as Microsoft starts the slow process of restoring Office docs and source code (!) they will discover what the rest of us have known all along -- the security model is less than ideal (which is, um, an understatement). Another interesting note, the APIs that the Exchange Anti-Virus vendors use to scan Exchange mailstores only scan on messages inbound to the mailstore. This means that outbound messages are not scanned. We had an affected machine that replied to messages from the Internet with the trojan attachment as our Exchange outbound goes straight to a Unix machine on its way to the Internet. Fortunately we had a process running on the Unix box to catch inbound and outbound email with the attachments named zipped_files.exe and it was stopped, but this was why we saw our Exchange AntiVirus *not* catch the message. Why do the Anti-Virus vendors only use APIs that catch inbound messages? Because that is all Microsoft has given them. Most of the vendors have really been pressuring Microsoft to release info about coding to check for outbound messages. Final tidbits (sorry if this message isn't very coherent, it's late and I've been up a long time): the trojan was written using Borland Delphi, and was possibly compiled on April 14, 1999. Obviously the virus writer got the idea for the propagation method from Melissa, and one can only wonder what the next worm/trojan/virus will do. Simple Nomad // thegnomeat_private // ....no rest for the Wicca'd.... www.nmrc.org //
This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 14:49:01 PDT