SCO Unixware Setuid ppp prompt Buffer Overflow Vulnerability

iDEFENSE Security Advisory 10.24.05
http://www.idefense.com/application/poi/display?type=vulnerabilities
October 24, 2005

I. BACKGROUND

SCO UnixWare is a UNIX operating system.

More information is available at:

  http://www.sco.com/products/unixware714/

II. DESCRIPTION

Local exploitation of a buffer overflow vulnerability in the ppp binary,

as included in multiple versions of The SCO Group Inc.'s Unixware, 
allows attackers to gain root privileges.

The vulnerability specifically exists because of a failure to check the 
length of user input. If the user running the ppp program enters an 
argument to the "prompt" or "defprompt" command that exceeds 256 bytes
in 
length, a stack based overflow occurs. This leads to the execution of 
arbitrary code with root privileges, as ppp is setuid root by default.

III. ANALYSIS

Successful exploitation of this vulnerability requires that user have 
local access to the system; it would allow the user to gain superuser 
privileges.

IV. DETECTION

iDEFENSE has confirmed the existence of this vulnerability in SCO 
Unixware versions 7.1.3 and 7.1.4. All versions of SCO Unixware are 
suspected to be vulnerable.

V. WORKAROUND

As a workaround solution, remove the setuid bit from the backupsh binary

until a vendor patch can be applied.

  # chmod u-s /usr/bin/ppp 

VI. VENDOR RESPONSE

The vendor has released the following advisory for this issue:

  ftp://ftp.sco.com/pub/updates/UnixWare/SCOSA-2005.41/SCOSA-2005.41.txt

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2005-2927 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

09/08/2005  Initial vendor notification
09/09/2005  Initial vendor response
10/24/2005  Public disclosure

IX. CREDIT

iDEFENSE Labs is credited with the discovery of this vulnerability.

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X. LEGAL NOTICES

Copyright (c) 2005 iDEFENSE, Inc.

Permission is granted for the redistribution of this alert
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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.