Anon Proxy Server <= 0.102 remote buffer overflow Feb 03 2008 07:09PM
L4teral (l4teral gmail com)
Anon Proxy Server <= 0.102 remote buffer overflow

Author: L4teral <l4teral [4t] gmail com>
Impact: remote buffer overflow
Status: patch available

Affected software description:

Application: Anon Proxy Server
Version: <= 0.102
Vendor: http://anonproxyserver.sourceforge.net

A fast http, https, socks caching proxy server.
Easy web based configuration, optional p2p anonymous mode.


When user authentication is enabled, the server can be exploited by
passing a long username containing quotes. The username is checked
for length, but the function strquotecpy() in the file access.c
escapes quote characters by prepending a backslash, enlarging
the string without checking it for the resulting length.


Use the following perl code to generate a username triggering
the buffer overflow when used for authentication:

print "A" x 430 . '"' x 29 . "A" x 40 . "\n";

The program will catch the exception and restart itself - attach a
debugger to see the EIP overwrite.


Upgrade to version 0.103 or higher.


2008-01-27 - vendor informed
2008-01-28 - vendor released patch
2008-02-03 - public disclosure

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