| Submit your comments on this article |
| Science & Technology |
| Computer virus downloads a virus checker to remove other viruses |
| 2006-10-22 |
| Veteran malware researcher Joe Stewart was fairly sure he'd seen it all until he started poking at the SpamThru Trojan—a piece of malware designed to send spam from an infected computer. The Trojan, which uses peer-to-peer technology to send commands to hijacked computers, has been fitted with its own anti-virus scanner—a level of complexity and sophistication that rivals some commercial software. "This the first time I've seen this done. [It] gets points for originality," says Stewart, senior security researcher at SecureWorks, in Atlanta, Ga. "It is simply to keep all the system resources for themselves—if they have to compete with, say, a mass-mailer virus, it really puts a damper on how much spam they can send," he added. Most viruses and Trojans already attempt to block anti-virus software from downloading updates by tweaking hosts file to the anti-virus update sites to the localhost address. Malicious hackers battling for control over an infected system have also removed competing malware by killing processes, removing registry keys, or setting up mutexes that fool the other malware into thinking it is already running and then exiting at start. But, as Stewart discovered during his analysis, SpamThru takes the game to a new level, actually using an anti-virus engine against potential rivals. At start-up, the Trojan requests and loads a DLL from the author's command-and-control server. This then downloads a pirated copy of Kaspersky AntiVirus for WinGate into a concealed directory on the infected system. It patches the license signature check in-memory in the Kaspersky DLL to avoid having Kaspersky refuse to run due to an invalid or expired license, Stewart said. Ten minutes after the download of the DLL, it begins to scan the system for malware, skipping files which it detects are part of its own installation. "Any other malware found on the system is then set up to be deleted by Windows at the next reboot," he added. At first, Stewart said he was confused about the purpose of the Kaspersky anti-virus scanner. "I theorized at first that distributed scanning and morphing of the code before sending the updates via P2P would be a clever way to evade detection indefinitely," he said, but it wasn't until he looked closely at the way rival malware files were removed that he realized this was a highly sophisticated operation working hard to make full use of stolen bandwidth for spam runs. Stewart also found SpamThru using a clever command-and control structure to avoid shutdown. The Trojan uses a custom P2P protocol to share information with other peers—including the IP addresses and ports and software version of the control server. "Control is still maintained by a central server, but in case the control server is shut down, the spammer can update the rest of the peers with the location of a new control server, as long as he/she controls at least one peer," he said. Stewart found that the network generally consists of one control server (running multiple peer-nets on different ports), several template servers, and around 500 peers per port. There appears to be a limit to how many peers each port can effectively control, as the overhead in sharing information between hosts is fairly large, he added. "The estimated number of infected hosts connected to the one control server we looked at was between one and two thousand across all open ports," Stewart added. The operation uses template-based spam, setting up a system where each SpamThru client is its own spam engine, downloading a template containing the spam, random phrases to use as hash-busters, random "from" names, and a list of several hundred e-mail addresses to send advertising. The templates are encrypted and use a challenge-response authentication method to prevent third parties from being able to download the templates from the template server. Stewart also found that the Trojan was randomizing the GIF files—changing the width and height of the images—to defeat anti-spam solutions that reject e-mail based on a static image. "Although we've seen automated spam networks set up by malware before, this is one of the more sophisticated efforts. The complexity and scope of the project rivals some commercial software. Clearly the spammers have made quite an investment in infrastructure in order to maintain their level of income," Stewart said. During his analysis, Stewart found that SpamThru was being used to operate a spam-based pump-and-dump stock scheme. |
| Posted by:3dc |
| #10 Nothing's new under the sun! In 90 or 91 I'm not sure, my computer, with MS-DOS only, was infected by a virus called Stoned from a floppy with an anti-virus scan package on it. |
| Posted by: SwissTex 2006-10-22 23:31 |
| #9 My Z-80 CP/M machine in the corner never gets viruses or spam. Seriously, there is a simply answer to 90% of spam. Charge $0.01 for each copy of an eMail you send out, and reduce fixed monthly or hourly charges appropriately. Of course, you would have to get everyone, in every country, to agree to this; any one hold-out would become the spam-haven. Oh, well, as Winston Churchill said: "They say the world has become too complex for simple answers. They are wrong. There are no easy answers, but there are simple answers." (I see that RR has been credited with this, also.) |
| Posted by: Jackal 2006-10-22 22:02 |
| #8 Microsoft is the virus. |
| Posted by: Iblis 2006-10-22 20:59 |
| #7 Veteran malware researcher Joe Stewart was fairly sure he'd seen it all until he started poking at the SpamThru Trojan—a piece of malware designed to send spam from an infected computer. The Trojan, which uses peer-to-peer technology to send commands to hijacked computers, has been fitted with its own anti-virus scanner—a level of complexity and sophistication that rivals some commercial software. "This the first time I've seen this done. [It] gets points for originality," says Stewart, senior security researcher at SecureWorks, in Atlanta, Ga. Think of it as evolution in action. |
| Posted by: Jonathan 2006-10-22 17:09 |
| #6 One of my sons worked at a computer repair shop for a couple of years. I'll tell you what we need based on his experience: We need computer owners to install anti-virus software and keep it updated. There are far too many computers out there that have either (1) never had anti-virus software or (2) have it pre-installed but not actuated or (3) have it actuated but never updated. The driving analogy would be if there were far too many drivers on the road who never bothered to turn on their headlights -- even at night. They would inconvenience all of us by forcing us to drive slower, causing accidents, forcing detours around accidents, and cloging up our police and legal systems. If you are reading this and you do not know for a fact that you have operating, up-to-date anti-virus software, then kill your computer power right now, unplug you computer, haul it out to the dumpster, and never access the internet again. You are unworthy. |
| Posted by: Darrell 2006-10-22 15:10 |
| #5 Prosecute spammers for theft of service. Prosecute them for illegal access to computer systems. Prosecute them for the fraud or obscenity INVARIABLY involved in what they're spamming. Also need to nail those ISPs that sell service to spammers. |
| Posted by: Pappy 2006-10-22 11:45 |
| #4 devise a new email SMTP protocol. Why? WTF does SMTP have to do with a POS mail reader that executes every damned piece of scripting it comes across? SMTP doesn't just work fine, it works brilliantly. Stop using crap mail readers, or at least stop using them like brainless dinks, and 99.99999% of the trojans go away. You want to end spam? Yeah, who doesn't. It's not a technology problem, though. SMTP didn't create the problem; human scum created the problem. Get rid of the scum, and the problem goes away. Prosecute spammers for theft of service. Prosecute them for illegal access to computer systems. Prosecute them for the fraud or obscenity INVARIABLY involved in what they're spamming. Hell, prosecute people who respond to spam; if you can charge someone for soliciting a prostitute, why not charge someone for responding to a stock fraud, a pyramid scheme, or child pron. If you're stupid enough to believe a Nigerian scammer, you're too stupid to be accorded the full rights of an adult citizen -- we'd all be better off if you were in prison or at least banned from the 'net. |
| Posted by: Rob Crawford 2006-10-22 09:52 |
| #3 Why do they hate us? |
| Posted by: Dunno 2006-10-22 05:08 |
| #2 No, anon1, we need to implement IPv6 and devise a new email SMTP protocol. However, this specific case is related to inherent wulnerabilities in windoze MS apps' spagetti code and open raw sockets that enable spam trojans to create armies of zombie machines. |
| Posted by: twobyfour 2006-10-22 03:00 |
| #1 we need a new internet |
| Posted by: anon1 2006-10-22 02:09 |