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SCO Unixware Setuid ppp prompt Buffer Overflow Vulnerability

10.24.05

BACKGROUND

SCO UnixWare is a UNIX operating system.

More information is available at:

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

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.

ANALYSIS

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

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.

WORKAROUND

As a workaround solution, remove the setuid bit from the ppp binary
until a vendor patch can be applied.

  # chmod u-s /usr/bin/ppp

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

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.

DISCLOSURE TIMELINE

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

CREDIT

iDEFENSE Labs is credited with the discovery of this vulnerability.

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LEGAL NOTICES

Copyright © 2005 Verisign, Inc.

Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
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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.