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TITLE:
UltraVNC "ClientConnection" Signedness Vulnerabilities

SECUNIA ADVISORY ID:
SA33794

VERIFY ADVISORY:
http://secunia.com/advisories/33794/

CRITICAL:
Moderately critical

IMPACT:
System access

WHERE:
>From remote

SOFTWARE:
UltraVNC (formerly Ultr@VNC) 1.x
http://secunia.com/advisories/product/2836/

DESCRIPTION:
Some vulnerabilities have been reported in UltraVNC, which
potentially can be exploited by malicious people to compromise a
user's system.

The vulnerabilities are caused due to signedness errors within the
"ClientConnection::CheckBufferSize()" and
"ClientConnection::CheckFileZipBufferSize()" functions in
ClientConnection.cpp. This can be exploited to cause a heap-based
buffer overflow by e.g. tricking a user into connecting to a
malicious VNC server.

The vulnerabilities are reported in version 1.0.2 and 1.0.5. Other
versions may also be affected.

SOLUTION:
Update to UltraVNC vncviewer 1.0.5.4.
http://www.uvnc.com/download/1054/

PROVIDED AND/OR DISCOVERED BY:
Ariel Futoransky, Fernando Russ, and Alfredo Ortega from Core
Security Technologies

ORIGINAL ADVISORY:
UltraVNC:
http://forum.ultravnc.info/viewtopic.php?t=14654

Core Security Technologies:
http://www.coresecurity.com/content/vnc-integer-overflows

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