Last revised: May 15, 2002
Source: CERT/CC
A complete revision history can be found at the end of this file.
The rwall daemon (rpc.rwalld) is a utility that is used to listen for
wall requests on the network. When a request is received, it calls wall,
which sends the message to all terminals of a time-sharing system. A
format string vulnerability may permit an intruder to execute code with
the privileges of the rwall daemon. A proof of concept exploit is publicly
available, but we have not seen active scanning or exploitation of this
vulnerability.
rpc.rwalld is a utility that listens for remote wall requests. Wall is
used to send a message to all terminals of a time-sharing system. If the
wall command cannot be executed, the rwall daemon will display an error
message.
An intruder can consume system resources and potentially prevent wall
from executing, which would trigger the rwall daemon's error message. A
format string vulnerability exists in the code that displays the error
message. This vulnerability may permit the intruder to execute code with
the privileges of the rwall daemon.
This vulnerability may be exploited both locally and remotely, although
remote exploitation is significantly more difficult.
An intruder can execute code with the privileges of the rwall daemon,
typically root.
Apply a patch Appendix A contains information provided by
vendors for this advisory.
If a patch is not available, disable the rwall daemon (rpc.rwalld) in
inetd.conf until a patch can be applied.
If disabling the rwall daemon is not an option, implement a firewall to
limit access to rpc.rwalld (typically port 32777/UDP). Note that this will
not mitigate all vectors of attack.
This appendix contains information provided by vendors for this
advisory. As vendors report new information to the CERT/CC, we will
update this section and note the changes in our revision history. If a
particular vendor is not listed below, please check the Vulnerability Note
(VU#638099) or contact your vendor directly. Mac OS X does not contain rwall, and is not susceptible to the
vulnerability described.
BSD/OS does not include an affected daemon in any version.
Compaq Tru64 is NOT vulnerable to this reported problem.
Cray, Inc. is not vulnerable since the affected code is not included in
the rwalld implementation used in Unicos and Unicos/mk.
FreeBSD is not vulnerable to this problem.
HP is not vulnerable.
sent on May 15, 2002
[Server Products]
Sun is currently generating patches for this issue and will be
releasing a Sun Security Bulletin once the patches are available. The
bulletin will be available from:
Sun patches are available from:
The CERT Coordination Center acknowledges "GOBBLES" as the
discoverer of this vulnerability and thanks Sun Microsystems for
their technical information.
Feedback can be directed to the author: Jason
A. Rafail
Copyright 2002 Carnegie Mellon University. Revision History
Systems Affected
Overview
I. Description
II. Impact
III. Solution
Appendix A. - Vendor Information
Apple
BSDI
Compaq Computer Corporation
Cray, Inc.
FreeBSD
Hewlett-Packard
IBM
IBM's AIX operating system, versions 4.3.x and 5.1L, is not susceptible
to the vulnerability described.
NEC
- is NOT vulnerable.
NetBSD
NetBSD has never been vulnerable to this problem.
Sun Microsystems
Sun confirms that there is a format string vulnerability in
rpc.rwalld(1M) which affects Solaris 2.5.1, 2.6, 7 and 8. However, this
issue relies on a combination of events, including the exhaustion of
system resources, which are difficult to control by a remote user in order
to be exploited. Disabling rpc.rwalld(1M) in inetd.conf(4) is the
recommended workaround until patches are available.
http://sunsolve.sun.com/security
http://sunsolve.sun.com/securitypatch
May 1, 2002: Initial release
May 2, 2002: Added Apple vendor statment.
May 2, 2002: Added Compaq vendor statment.
May 2, 2002: Added Cray vendor statment.
May 2, 2002: Added FreeBSD vendor statment.
May 2, 2002: Added BSDI vendor statment.
May 15, 2002: Added NEC vendor statment.