Rafel Ivgi has discovered a weakness in Internet Explorer (IE), allowing malicious people to crash a user's browser.

Analysis indicates that the issue is caused due to an error during the construction of a file download error message dialog box like the following:

"Internet Explorer cannot download [file] from [server]"

It is possible to trigger the issue via a specially crafted link like:
<a href=::%7>Link</a>

This causes an incorrect pointer to be passed as argument in a call to "_snwprintf()" instead of the correct pointer to the string: "[file] from [server]". This may result in an access violation, if the pointer refers to an inaccessible memory location, which varies depending on the supplied value after the "%" character.

The problem has been confirmed on a fully patched system with IE 6.0. Other versions may also be affected.

Successful exploitation crashes the browser, if a user is tricked into right clicking the link and choosing "Save Target As...". It is currently not believed that this issue can be exploited for code execution purposes.

NOTE: Secunia would normally not classify a browser crash as a vulnerability nor issue an advisory about it. However, the potential risc of this issue being more severe than currently believed justified for an advisory being issued.

Solution
The weakness has been silently fixed at some point.

Provided and/or discovered by
Rafel Ivgi

Changelog
Further details available to Secunia VIM customers

Deep Links
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