The attack on ad-serving company Falk that redirected some Reg readers on Saturday towards a site running malicious code may be part of a much bigger attack.
Security site vitalsecurity.org reports that a group of hackers - perhaps a criminal gang - is hacking web servers across the net and installing root kits that dynamically inject code into the pages served from the compromised web servers. The injected code effectively serves as a "front door" to a series of compromised hosts controlled by cyber criminals. These rogue hosts are running exploit code that takes advantage of the IFRAME vulnerability in Internet Explorer exploited by the recent Bofra worm.
"This is similar to Download.Ject, only this time it works on Apache servers rather than Windows," explained Christopher Boyd of vitalsecurity. "Using IFRAME, a number of sites install anything up to 8MB worth of exploits on a user’s machine - viruses, Trojans, scripts, malware packages - you name it, you'll end up with it."
Software installed on victims' PCs varies from porn diallers to spyware and adware packages. According to Finnish anti-virus firm F-Secure, the activity reported by vitalsecurity began on Friday night (19 November) and remains ongoing. But so far victims seem to be thin on the ground.
"The interesting part here is the usage of the new IFRAME vulnerability, for which Microsoft still has no patch out. We urge users either to go with Windows XP with SP2 or to upgrade their Internet Explorer to any other browser," said Mikko Hyppönen, director of anti-virus research at F-Secure. "We haven't received huge amounts of reports from people who would have been actually hit by it (many wouldn't notice it, of course). Traces seem to end with updates.virtumonde.com [a Brazilian website]."
Acting with law enforcement authorities, Microsoft was able to rapidly shut down the Russian website, but the affair still highlighted security concerns with IE. Security clearing house US-CERT took the extraordinary step of advising users to ditch IE in favour of alternative browsers. Microsoft has since fixed the underlying flaw that Download.Ject exploited, but an IFRAME fix remains outstanding.
This time around the effects could be even more damaging. Vitalsecurity's Boyd reckons the installation of malware is been used to create a massive botnet. The purpose of this attack network remains unknown. "If you're an admin of an Apache box, you need to ensure that you are fully patched, especially in the area of OpenSSL exploit as this is where they seem to be gaining access to the servers," he urged. ®
Bofra exploit hits our ad serving supplier
Falk statement on Bofra attack
Bofra worm sets trap for unwary
Watch out! Incoming mass hack attack
Unpatched IE vuln exploited by adware
CERT recommends anything but IE
Download.Ject-style worm spreads via IM
Admins slow to tackle SSL security risks