Hackers are targeting a zero-day vulnerability affecting Adobe Reader and Acrobat with malicious PDF files. This vulnerability would cause the application to crash and could potentially allow an attacker to take control of the affected system. Hackers have been spreading malicious PDF files containing the Pidief Trojan. If a person opens the file, the Trojan attempts to exploit an unpatched processing error in Adobe Acrobat Reader 8 and 9, which results in a buffer overflow.
The bug is due to an error in the parsing of certain structures in PDF files. If exploited successfully, the bug could allow a hacker to take complete control of a vulnerable system. “In parsing a specially-crafted embedded object, a bug in the reader allowed the attacker to overwrite memory at an arbitrary location, The attacks, found in the field, use the infamous heap spray method via JavaScript to achieve control of code execution.” blogged McAfee researcher Geok Meng Ong.
In the meantime, security researchers at the Shadowserver Foundation recommend users consider disabling JavaScript. Symantec also recommended Adobe users keep their antivirus up-to-date. “While we continue to investigate this issue, customers are advised to follow best practices and only open email attachments from people they trust,” blogged Symantec researcher Patrick Fitzgerald. “Enabling DEP (Data Execution Prevention) for Adobe Reader will also help prevent this type of attack.”
Adobe acknowledged the zero-day in an advisory to customers calling it critical. It confirmed the flaw in Adobe Reader 9 and Acrobat 9 as well as Adobe Reader and Acrobat 8.1.3 and earlier versions. Adobe officials say a fix for the issue will be available for Adobe Reader and Adobe Acrobat in the coming weeks.