Rapid7 chief security officer HD Moore, who recently wrote two detailed blog posts on the subject, said in a phone interview that he expects Microsoft to release a security advisory or further information at some point on Monday.
Moore said he had stumbled across this class of DLL hijacking vulnerabilities while working on a Windows Shortcut exploit. He had planned to publish an advisory and to begin notifying vendors last week when Acros, a Slovenian security firm, published details about exploiting an old version of iTunes using a file on a remote network share.
Apple fixed this flaw in its iTunes 9.1 security update in March. But dozens of other Windows software vendors still need to deal with this issue.
According to Moore, maybe 40 or 50 applications appear to be vulnerable from a testing standpoint, though fewer will be vulnerable in practice. He said maybe 15 or 20 apps on a given desktop are likely to be affected.
"This vulnerability is triggered when a vulnerable file type is opened from within a directory controlled by the attacker," Moore explained in a blog post. "This directory can be a USB drive, an extracted archive, or a remote network share. In most cases, the user will have to browse to the directory and then open the target file type for this exploit to work."
The DLL flaw goes back about ten years, said Moore, and while past fixes have mitigated some of the risk, the issue has yet to be effectively dealt with.
A paper published earlier this year and presented in July at the International Symposium on Software Testing and Analysis 2010 describes this class of DLL loading vulnerabilities. The report's co-authors say that they used an automated tool to identity 1,700 unsafe DLL loadings in 28 widely used software applications and that Microsoft has been made aware of their findings.
Moore has updated his Metasploit Framework with a generic exploit module and audit kit to assist in the identification of vulnerable applications.
As of 3pm PST on Monday, Microsoft has not provided information about this issue on its security advisory Web site.
Update: Around 4pm PST, Microsoft published a security advisory covering DLL attacks.