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Zone Labs IMsecure Active Link Filter Bypassing
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SUMMARY
Zone Lab's IMsecure allows a user to further protect his computer from
malicious content by actively filtering potentially dangerous URLs
containing files with extensions such as vbs, scr and exe. A vulnerability
in the Zone Lab's IMsecure allows an attacker to bypass this protection by
encoding part of the extension.
DETAILS
Vulnerable Systems:
* ZoneLabs IMsecure and IMsecure Pro version 1.4 and prior
Immune Systems:
* ZoneLabs IMsecure and IMsecure Pro version 1.5
The active link filter is programmed to block any potentially dangerous
URLs in IM messages. For example, IMsecure will remove URLs with
extensions of .vbs, and .exe. By encoding characters in the file extension
of the URL, it is possible to bypass the Zone Lab's active link filtering
mechanism.
Proof of Concept:
While IMsecure's protection mechanism is enabled accessing:
http://www.example.com/somefile.e%78e would allow to download an otherwise
blocked executable file. In the example, "78" is the encoded form of "x".
ADDITIONAL INFORMATION
The information has been provided by Paul Kurczaba.
The original article can be found at:
<http://www.kurczaba.com/html/security/0410141.htm>
http://www.kurczaba.com/html/security/0410141.htm
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