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List:       bugtraq
Subject:    Lynx format string vulnerability in URL logging.
From:       "Larry W. Cashdollar" <lwc () vapid ! dhs ! org>
Date:       2001-12-27 17:23:01
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The vendor has been notified, but since this is a low risk I am
releasing early.


				Vapid Labs
			    Larry W. Cashdollar
				Bug Report

Summary: lynx has a format string vulnerability in LYUtils.c line 7995 due
	 to a bad call to syslog(), where the format argument is omitted.

Risk: Low

Version: Lynx compiled from FreeBSD ports collection.  Also tested in
2.8.5dev.5.gz

[larryc@harod ~ $] lynx --version
Lynx Version 2.8.4rel.1 (17 Jul 2001)
Built on freebsd4.4 Dec 25 2001 23:04:31


Details:

line 7995 in LYUtils.c reads:
syslog (LOG_INFO|LOG_LOCAL5, buf);

The reason this is low priority is the bug can only big triggered if
sysloging URL's is enabled.
(./configure --enable-syslog)

Exploit:

The following url triggers the bug:

[larryc@harod ~ $] lynx http://lwc%d%d:hsVd632k@vapid.dhs.org/bleh:80

Results in the following logged to syslog.

Dec 25 23:11:00 vapid lynx[5160]: http://lwc-1077939384134744128:******@vapid.dhs.org/bleh:80

Fix:

line 7995:
- -syslog (LOG_INFO|LOG_LOCAL5, buf);
+syslog (LOG_INFO|LOG_LOCAL5,"%s", buf);


Larry W. Cashdollar
http://vapid.dhs.org


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