Lynx format string vulnerability in URL logging.

From: Larry W. Cashdollar (lwcat_private)
Date: Thu Dec 27 2001 - 09:23:01 PST

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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 hsVd632kat_private/bleh:80">http://lwc%d%d:hsVd632kat_private/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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