Adobe is investigating new reports that hackers are attacking a previously unknown bug in the latest version of the company's Reader and Acrobat software.
"This afternoon, Adobe received reports of a vulnerability in Adobe Reader and Acrobat 9.2 and earlier versions being exploited in the wild," Adobe wrote in a post to its Product Security Incident Response Team (PSIRT) blog on Monday afternoon.
"We are currently investigating this issue and assessing the risk to our customers."
Adobe had few details on the reported problem. "As soon as we have additional details, we will update the PSIRT blog," a spokeswoman said in an e-mail message.
Adobe learned of the attack on Monday, said Brad Arkin, Adobe's director of product security and privacy. "Three different partners in the security community shared samples of the same attack with us within a few minutes of each other this afternoon," he said via instant message.
The criminals are exploiting this flaw by sending malicious PDF files to victims, according to the volunteer-run malware tracking group Shadowserver.
"This is legit and is very bad," Shadowserver said said in a post to its Web site late Monday. Shadowserver could not be reached immediately for comment.
Shadowserver said that several "tests have confirmed this is a 0-day vulnerability affecting several versions of Adobe Acrobat [Reader] to include the most recent versions of 8.x and 9.x. We have not tested on 7.x, but it may also be vulnerable."
The attack has been used by cybercriminals since at least Friday, but has not seen any widespread use, Shadowserver said. "Expect the exploit to become more wide spread in the next few weeks and unfortunately potentially become fully public within the same timeframe."
Most antivirus products do not yet detect the attack, Shadowserver noted.
With Reader and Acrobat installed on most of the world's PCs, the products have become an increasingly attractive target for computer hackers who take advantage of flaws in the system to run unauthorized programs on victims' PCs.