For the third time in two months, a zero-day vulnerability in a widely used Microsoft Office software application is being used in targeted hacker attacks.
The latest attack exploits a previously undocumented flaw in Microsoft PowerPoint, the ubiquitous presentation program used by millions of users around the world.
The attack comes just days after Microsofts July Patch Tuesday and closely mirrors the situation in June when a zero-day Excel attack was discovered 24 hours after Patch Day.
Virus hunters at Symantec linked the zero-day attack to a Trojan horse program called Trojan.PPDropper.B that arrives via e-mail from a Gmail address.
The subject line of the mail and the .ppt file-name are in Chinese characters, suggesting that the attacks are emanating from—and attacking targets—in the Far East.
If the PowerPoint attachment is opened, the Trojan drops and executes a variant of Backdoor.Bifrose.E, a keystroke logger that is used to steal sensitive information and send it back to a remote server controlled by malicious hackers.
The Trojan also injects a malicious routine into the EXPLORER.EXE process that overwrites the malicious PowerPoint file with a new clean copy of the document.
Anti-virus researchers believe this tactic is used to wipe traces of the computer breach.
A Microsoft spokesman described the attack as "extremely limited."
"In order for this attack to be carried out, a user must first open a malicious PowerPoint document that is sent as an e-mail attachment, posted to a Web site or otherwise provided to them by an attacker.
"On more recent versions of PowerPoint, opening the PowerPoint document out of e-mail will prompt the user to be careful about opening the attachment," the spokesman said in a statement sent to eWEEK.
The company is expected to issue a prepatch security advisory with guidance and workarounds to help customers block potential attacks.
According to Symantecs advisory, the PowerPoint flaw affects Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003 and Windows XP.
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