Mono ASP.NET Unicode Conversion Cross-Site Scripting

“Secunia Advisory: SA14325

Critical: Less critical

Impact: Cross Site Scripting

Where: From remote

Solution Status: Vendor Patch

Software: Mono 1.x

Andrey Rusyaev has discovered a vulnerability in Mono, which potentially can be exploited by malicious people to conduct cross-site scripting and script insertion attacks.

The vulnerability is caused due to an input validation error in the sanitation of special HTML characters supplied as unicode characters in the “Request Validation” security mechanism. This can e.g. be exploited to execute arbitrary HTML and script code in a user’s browser session in context of a vulnerable site via a script returning user input without sanitation.

This is similar to:
SA14214

Successful exploitation requires that the response encoding has been set to a national ASCII codepage (not default setting).

The vulnerability has been confirmed in version 1.0.6 and has also been reported in version 1.0.5. Other versions may also be affected.

Solution: The vulnerability has been fixed in the source repository.
* Mono 1.0.x fixed at revision r41110.
* Mono 1.1.x fixed at revision r41105.

Binary updates to System.Web.dll are available.

Mono 1.0.6: http://www.go-mono.com/archive/updates/1.0.6/System.Web.dll
md5sum: 558d94f99e159827f74205d9a75fa8b1

Mono 1.1.4:
http://www.go-mono.com/archive/updates/1.1.4/System.Web.dll
md5sum: 540ee1b0d3cefb104f8d2d37a2adf3ee”

Full article: Secunia Advisory: SA14325