Rodrigo Gutierrez has discovered a vulnerability in Windows and Internet Explorer, which can be exploited by malicious people to compromise a user's system.

The vulnerability is caused due to a boundary error, which can be triggered via Internet Explorer and Windows Explorer when connecting to a file server. This can be exploited to cause a buffer overflow by setting up a malicious share with an overly long name (about 300 bytes) containing no lower case characters.

Successful exploitation may potentially allow execution of arbitrary code on a user's system but requires that the user is either tricked into connecting to a malicious file server, visit a malicious website, or follow a specially crafted link.

According to a Microsoft knowledge base article (see "Other References" section), the vulnerability should have been fixed in SP1 for Windows XP and SP4 for Windows 2000. However, the vulnerability has been confirmed on fully patched systems running Windows XP SP1 and Windows 2000 SP4.

The vulnerability has also been reported in Windows 95, 98, Me, and NT 4.0. Systems running Windows 2003 are reportedly not affected.

NOTE: Secunia would normally rate this kind of vulnerability as "Moderately critical", since this kind of traffic should be restricted to a LAN via border routers and firewalls. However, this is not the case on many networks, which leads to the higher rating.

Solution
The variant of the vulnerability has been fixed at some point. Ensure that systems are fully updated.

Provided and/or discovered by
Rodrigo Gutierrez

Changelog
Further details available to Secunia VIM customers

Other references
Further details available to Secunia VIM customers

Deep Links
Links available to Secunia VIM customers