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iDEFENSE Security Advisory 11.01.02: 
http://www.idefense.com/advisory/11.01.02.txt
Buffer Overflow Vulnerability in Abuse
October 31, 2002

I. BACKGROUND

Abuse is a popular side-scrolling video game. More information can be
found at http://jonathanclark.com/ and http://www.crack.com/.

II. DESCRIPTION

Exploitation of a locally exploitable parsing error in Abuse's "-net"
command line option could allow attackers to gain root privileges on
a targeted system. By supplying an overly long argument, the
instruction pointer is overwritten, thereby allowing an attacker to
seize control of the executable. In a default abuse installation in
Debian Linux, both abuse.console and abuse.x11R6 can be used in
exploitation; both files are set group id games, and abuse.console is
set user id root.

III. ANALYSIS

Exploitation allows a local attacker to gain super-user status and
full control over the targeted system. Affected users should
implement either of the two workarounds listed below.

IV. DETECTION

Abuse 2.00, which is packaged and distributed with the x86
architecture of Debian Linux 3.0r0, is vulnerable. Other platforms
and architectures may be vulnerable as well. To determine if a
specific Abuse implementation is vulnerable, launch it with the
following command line:

$ /usr/lib/games/abuse/abuse.console -net 'perl -e 'print "A"x500''

If the application crashes with a "Segmentation fault", it is
vulnerable.

V. WORKAROUND

Customers should consider implementing one of the two following
workarounds:

1. Remove Abuse by issuing the following command:

# apt-get remove abuse 

2. Remove the setuid bit from the XaoS binary by executing the
following command:

# chmod -s /usr/lib/games/abuse/abuse.*

VI. VENDOR RESPONSE

"Abuse has a number of other vulnerabilities and should never be
installed on a multi-user system where security is a concern," said
Jonathan Clark.

"Abuse allows alternate Lisp script files to be executed at startup
via command line parameters.  Some script functions can execute
abritrary commands or cause external files to modified."

VII. CVE INFORMATION

The Mitre Corp.'s Common Vulnerabilities and Exposures (CVE) Project
assigned the identification number CAN-2002-1250 to this issue.

VIII. DISCLOSURE TIMELINE

10/15/2002	Issue disclosed to iDEFENSE
10/31/2002	Author notified
10/31/2002	iDEFENSE clients notified
11/01/2002	Response received from Jonathan Clark 
		(jc@jonathanclark.com)
11/01/2002	Public disclosure

IX. CREDIT

Texonet (http://www.texonet.com) discovered this vulnerability.


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and other malicious code. Our security intelligence services provide 
decision-makers, frontline security professionals and network 
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and decision support on cyber-related threats. For more information,
visit http://www.idefense.com.


- -dave

David Endler, CISSP
Director, Technical Intelligence
iDEFENSE, Inc.
14151 Newbrook Drive
Suite 100
Chantilly, VA 20151
voice: 703-344-2632
fax: 703-961-1071

dendler@idefense.com
www.idefense.com

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