Hackers are aggressively exploiting a just-patched Flash vulnerability, serving attack code "on a fairly large scale" from compromised sites as well as from their own malicious domains, a security researcher said Friday.
The attacks exploit the critical Flash Player bug that Adobe patched June 14 with its second "out-of-band," or emergency update, in nine days.
"CVE-2011-2110 is being exploited in the wild on a fairly large scale," said Steven Adair, a researcher with the Shadowserver Foundation, a volunteer-run group that tracks vulnerabilities and botnets. "In particular this exploit is showing up as a drive-by in several legitimate websites, including those belonging to various NGOs [non-government organizations], aerospace companies, a Korean news site, an Indian government Web site, and a Taiwanese university."
CVE-2011-2110 is the identifier for the Flash vulnerability assigned by the Common Vulnerabilities and Exposures database.
Attackers are also using the exploit in "spear phishing" attacks aimed at specific individuals, said Adair on the Shadowserver site.
Adair called the attacks "nasty" because the exploit "happens seamlessly in the background," giving victims no clue that their systems have been compromised.
When Adobe patched the vulnerability last week, it conceded that exploits were already in use.
Adair also said there's been an increase in Flash-based attacks. "There has been an ongoing assault against Flash Player for several years now, but especially so in the last three months," Adair said.
Adobe has patched Flash Player four times in the last two months, and six times so far this year. Of the six updates, five addressed "zero-day" bugs that attackers were already exploiting at the time the patches were issued.
Brad Arkin, Adobe's director of product security and privacy, acknowledged the problems in keeping ahead of attackers, but blamed the popularity of Flash Player for the attention.
"The installed base [of Flash Player] is a real big part of it," said Arkin. "It's such a widely distributed technology that attackers find it worthwhile to invest the time to carry out some kind of malicious activity. They're making an investment for the biggest return possible."
Arkin also argued that attackers get more bang for their buck by rooting out Flash vulnerabilities than they do looking for bugs in individual browsers because virtually every personal computer has the Flash plug-in installed. "Flash is the code [used in the browser] that has the highest market penetration," he said.
According to Adair, the exploit of CVE-2011-2110 has been in use since June 9, five days before Adobe issued its latest security update. Arkin corroborated that timeline.
Although Adobe's working on boosting Flash's security -- it's collaborated with Google, for example, to sandbox Flash in Chrome -- for now, its best defense is to quickly react to exploits with a patch.
"I think we're more aggressive than Microsoft," said Arkin, referring to the two companies' approaches to shipping out-of-band updates. "Basically, if we have information about attacks in the wild, or if the information is out there on a [security] mailing list -- which means attacks are imminent -- that tends to be a trigger for us to think about an out-of-band."
Microsoft's criteria for deciding whether to issue an emergency patch is confidential, but the company has said it generally considers an out-of-band fix if it sees attacks increasing in volume.
By pushing out a patch as quickly as possible, Adobe believes it squelches discussion among security researchers and attackers.
"If there are attacks in the wild, there will be lots of blog posts analyzing the vulnerability and exploit," said Arkin. "The information migrates from the high end to the low end very quickly. So we squash the debate by fixing it."
Arkin said Adobe has focused on getting patches out quickly, and that the fix for an earlier Flash vulnerability -- one Adobe released June 5 -- had a turn-around of less than 72 hours.
"The more practice we have, the faster we turn around [patches]," Arkin said.
Adair urged everyone to keep Flash Player up-to-date. "If you or your organization runs Adobe Flash and you're not keeping up on these patches ... you are in bad shape," he said.
The newest version of Flash Player can be downloaded from Adobe's Web site. Alternately, users can run the program's integrated update tool or wait for the software to prompt them that a patched edition is available.