Cisco Pinpoints 'Here You Have' Worm's Virulence

Why was the "Here you have" -- aka "Just for you" -- mass-mailing worm able to move so quickly, and infect so many Windows PCs, and just what was its purpose?

To briefly recap: On Thursday, the now defunct malware moved at lightning speed through corporate e-mail systems and via network shares, e-mailing itself to everyone in a compromised PC's Outlook address book with a message that asked the receiver to open a malicious file disguised as a PDF. Numerous organizations were reportedly affected, including ABC, Comcast, Google, and NASA.

Without a doubt, the worm spread rapidly and in great volume. Cisco says that at the worm's peak -- at 6:30 p.m. UTC on September 9 -- it accounted for 14.2% of all global spam.

One culprit for the worm's rapid spread may have been Web-based e-mail accounts. "Even in some protected networks, which may have been filtering their own corporate e-mail traffic, employees checking personal inboxes like Gmail were going outside of the corporate e-mail filters and onto the web, where in too many instances there isn't sufficient web filtering," said Nilesh Bhandari, a product manager at Cisco.

Another likely culprit was the worm's ability to propagate via open network shares, which isn't typical, meaning that many network defenses didn't see it moving, and thus didn't quarantine it in spam traps.

Likewise, by e-mailing everyone in a person's address book, the malware escaped spam detectors, since the e-mails went from legitimate senders to legitimate recipients. "So e-mails appeared to be coming from someone known," said Bhandari. "This caused rapid and broad, unfiltered penetration."

Besides moving quickly and infecting many different computers, what was the worm for?

On Sunday, the hacker "iraq_resistance," founder of a cyber-jihad organization called "Brigades of Tariq ibn Ziyad," took credit for the attack in a YouTube video. "United States doesn't have the right to invade our people and steal the oil under the name of nuclear weapons," said a computerized voice in the video.

According to Joe Stewart, director of malware at SecureWorks, the hacker's claim appears to be legitimate. For starters, the "Here you have" attack resembled one seen in August 2010 that had [email protected] in the sender field. Various other clues in the second attack also point to its originating from the Brigades of Tariq ibn Ziyad.

Interestingly, iraq_resistance, who Stewart suspects is Libyan, has a history of seeking similarly minded recruits online, querying message boards for programming tips which later turn up in attacks, and bragging about exploits. For example, in a 2008 forum posting, said Stewart, the hacker "tries to get joiners to his Brigades of Tariq ibn Ziyad, whose goal is 'to penetrate U.S. agencies belonging to the U.S. Army.'"