Public Vulnerability Reports

Perl win32_stat Function Buffer Overflow Vulnerability

04.05.04

BACKGROUND

Perl is a popular programming language due to its text manipulation
capabilities and rapid development cycle. It is open source, cross
platform and used for mission critical projects in the public and
private sector.

DESCRIPTION

Remote exploitation of a buffer overflow in the 'win32_stat' function of
ActiveState's ActivePerl and Larry Wall's Perl could allow for the
execution of arbitrary commands.

If the filename passed to the function ends with a backslash character,
it is copied into a fixed length buffer. There is no check made on the
length of the string before the copy, allowing an excessively long
string to overwrite control information, allowing execution of arbitrary
code.

The problem specifically exists within the win32 wrapper to the stat()
routine and hence the Unix builds of Perl are not affected.

ANALYSIS

The 'win32_stat' function is a wrapper around the 'stat' function and
the file test operators ('-r', '-w', '-e', '-d' etc) on Win32 based
platforms.

If a web site contains a Perl script that uses any of these functions
with user supplied pathnames, it may be possible to remotely execute
commands.

DETECTION

All versions of Perl for Win32 operating systems up to and including
5.8.3 are affected.

VENDOR RESPONSE

The fix will be incorporated into core Perl 5.8.4. Patches are currently
available at the following locations:

Committed to the Perl 5.9.x development branch:

   http://public.activestate.com/cgi-bin/perlbrowse?patch=22466

Integrated into Perl 5.8.x maintenance branch as part of:

   http://public.activestate.com/cgi-bin/perlbrowse?patch=22552

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2004-0377 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

CREDIT

Greg MacManus (iDEFENSE Labs) is credited with this discovery.

Get paid for vulnerability research
http://www.idefense.com/poi/teams/vcp.jsp

LEGAL NOTICES

Copyright © 2004 Verisign, Inc.

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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
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