[ GLSA 200410-29 ] PuTTY: Pre-authentication buffer overflow

[GLSA]

Gentoo Linux Security Advisory

Title: PuTTY: Pre-authentication buffer overflow (GLSA 200410-29)
Severity: normal
Exploitable: remote
Date: October 27, 2004
Updated: May 22, 2006
Bug(s): #69123
ID: 200410-29

Synopsis


PuTTY contains a vulnerability allowing an SSH server to execute arbitrary
code on the connecting client.


Background


PuTTY is a free implementation of Telnet and SSH for Win32 and Unix
platforms, along with an xterm terminal emulator.


Affected Packages

Package: net-misc/putty
Vulnerable: <= 0.55
Unaffected: >= 0.56
Architectures: All supported architectures


Description


PuTTY fails to do proper bounds checking on SSH2_MSG_DEBUG packets. The
"stringlen" parameter value is incorrectly checked due to signedness
issues. Note that this vulnerability is similar to the one described in
GLSA 200408-04 but not the same.


Impact


When PuTTY connects to a server using the SSH2 protocol, an attacker
may be able to send specially crafted packets to the client, resulting
in the execution of arbitrary code with the permissions of the user
running PuTTY. Note that this is possible during the authentication
process but before host key verification.


Workaround


There is no known workaround at this time.


Resolution


All PuTTY users should upgrade to the latest version: