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UltraVNC vncviewer "ClientConnection::NegotiateProtocolVersion()" Buffer Overflow
Secunia Advisory: SA28747
Release Date: 2008-02-01
Last Update: 2008-03-17
Popularity: 9,068 views

Critical:
Moderately critical
Impact: System access
Where: From remote
Solution Status: Vendor Patch

Software:UltraVNC (formerly Ultr@VNC) 1.x

Binary Analysis: BA377 :: Available for 1 Credit

Secunia CVSS-2 Score: Available in Secunia business solutions

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Advisory Content (Page 1 of 3)[ 1 ] [ 2 ] [ 3 ]

Description:
A vulnerability has been discovered in UltraVNC, which can be exploited by malicious people to compromise a user's system.

The vulnerability is caused due the "ClientConnection::NegotiateProtocolVersion()" function in vncviewer/ClientConnection.cpp using user-supplied length values to copy data without proper bounds checking. This can be exploited to cause a stack-based buffer overflow by e.g. sending specially crafted data to a vncviewer in "LISTENING" mode or by tricking a user into connecting to a malicious VNC server.

Successful exploitation allows execution of arbitrary code.

This may also be exploited if a DSM plugin is used, but requires that the attacker owns the encryption key used by vncviewer.

The vulnerability is confirmed in version 1.0.2 and reported in release candidates of version 1.0.4 prior to January 25th, 2008. Reportedly, UltraVNC server is not affected.

Change Page:
[ 1 ] [ 2 ] [ 3 ]



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