Igor Franchuk has discovered a weakness in Microsoft Windows, which can be exploited to hide certain information.

The weakness is caused due to an error in the Registry Editor Utility (regedit.exe) when handling long string names. This can be exploited to hide strings in a registry key by creating a string with a long name, which causes this string and any subsequently created strings in the key to be hidden.

Successful exploitation e.g. makes it possible for malware to hide strings in the "Run" registry key. However, these hidden strings created after the string with the overly long name will still be executed when the user logs in.

The same problem reportedly also exists for overly long registry keys.

The weakness has been confirmed in fully updated Windows XP SP2 and Windows 2000 SP4 systems. Other versions may also be affected.

NOTE: The "regedt32.exe" utility on Windows 2000 is also affected, but in a slightly different way.

NOTE: A virus is reportedly exploiting this method to hide in the registry.

Solution
It's possible to see hidden registry strings with the "reg" command line utility.
Further details available to Secunia VIM customers

Provided and/or discovered by
Igor Franchuk

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