[3243] in bugtraq
rwhod buffer overflow
daemon@ATHENA.MIT.EDU (David J. Meltzer)
Wed Aug 21 18:03:40 1996
Date: Wed, 21 Aug 1996 16:38:57 -0400
Reply-To: Bugtraq List <BUGTRAQ@NETSPACE.ORG>
From: "David J. Meltzer" <davem@iss.net>
X-To: linux-security@tarsier.cv.nrao.edu, freebsd-security@freebsd.org,
deraadt@theos.com
To: Multiple recipients of list BUGTRAQ <BUGTRAQ@NETSPACE.ORG>
In-Reply-To: <199607240541.BAA18220@hcs.HARVARD.EDU>
There is a remote buffer overflow in the path variable in rwhod.c in the
line: (void) sprintf(path, "whod.%s", wd.wd_hostname);
Although wd_hostname is defined to be only 32 characters, it is read as
part of the wd structure from a remote host through a UDP packet and can
be as large as the remainder of the structure starting at that point.
Through examining the source this appears to be a problem in current
OpenBSD, NetBSD, FreeBSD, and Linux distributions. Through penetration
testing I have also found this problem present on AIX; I have not examined
other platforms running rwhod and so do not know about their potential
vulnerability.
I have succesfully exploited this remotely to produce undesirable effects
(segfaults and overwriting argv[0] on different OSes), I have not spent
sufficient time on this to determine exactly how/if to compromise root
directly with this overflow, but it is definitely something that should be
corrected.
I would suggest prior to the sprintf line you add something to the effect:
if(strlen(wd.wd_hostname) >= sizeof(wd.wd_hostname)) {
syslog(LOG_WARNING, "possible hostname overflow attack apparently from %x",
from.sin_addr);
continue;
}
Program: /usr/sbin/rwhod
Affected Operating Systems: OpenBSD, NetBSD, FreeBSD, Linux, AIX, others.
rwhod must be running on the system
Requirements: Ability to send UDP packet to target host
Security Compromise: Possible denial of service, Possible annoyance,
Possibly root compromise?
Author: Dave M. (davem@iss.net)
Synopsis: rwhod reads a structure from a udp packet and
does not check the hostname member of the
structure for being the expected size.
--------------------------------+---------------------
David J. Meltzer | Email: davem@iss.net
Systems Engineer | Web: www.iss.net
Internet Security Systems, Inc. | Fax: (404)252-2427
--------------------------------+---------------------
David J. Meltzer | Email: davem@iss.net
Systems Engineer | Web: www.iss.net
Internet Security Systems, Inc. | Fax: (404)252-2427
