Symantec: Another Surge In Worm Scanning For Unpatched AV Software

Sensors monitored by Symantec's DeepSight threat management service have reported a significant spike in traffic related to TCP port 2967, which Symantec has traced to scans generated by the "Sagevo" worm, recently released malware looking for systems running some of the company's enterprise antivirus software.

Flaws in both Symantec AntiVirus and Symantec Client Security were revealed in May and patched that same month. Sagevo, however, looks for unpatched machines, then tries to gain control of them.

Symantec reported that the number of sensors detecting scans of port 2097 were up over an uptick earlier in the week. "This is the most significant spike observed to date since the discovery of malicious code targeting the associated service," Symantec said in an alert to DeepSight subscribers.

"These scans are arriving in waves," says Vincent Weafer, senior director with Symantec's security response team. "When [the worm] is on an infected machine, it creates 512 threads on the box, and scans sequentially from the bottom up. [Meanwhile] any infected machines below that [IP address] also scan at the same time."

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The most recent wave of scans had already crested, Weafer says. "The number of infected machines remains small, about 70."

Symantec's written alert, however, noted that the worm's slow propagation was not only unusual, but could also change at any time.

"With minimal effort this worm could be modified so that the hardcoded IP address is replaced with the address of the attacking computer," read the warning issued Friday by the DeepSight system. "This would significantly increase the propagation capabilities of this worm.

"The potential of this simple modification should be enough to convince administrators to deploy patches if they are not already deployed."

The hard-coded IP address mentioned in the alert is the server -- which has been offline all week -- that the worm connects to after an infection. The downed server means that Sagevo cannot replicate to other machines from an infected PC. "This is a strange feature of the malicious code," read the DeepSight warning, "and could indicate a testing phase. The behavior is more indicative of bot behavior rather than traditional worms."

Fixes for the AntiVirus and Client Security vulnerabilities that Sagevo exploits have been available since late May on the Symantec support site.