NSFOCUS Security Advisory(SA2001-07)

Topic:  ActivePerl PerlIS.dll Remote Buffer Overflow Vulnerability

Release Date： 2001-11-15

CVE CAN ID : CAN-2001-0815
BUGTRAQ ID : 3526

Affected system:
================

Activestate ActivePerl 5.6.1.629 and earlier versions
 - Microsoft IIS 4.0
 - Microsoft IIS 5.0

Not affected system:
====================

Activestate ActivePerl 5.6.1.630
 - Microsoft IIS 4.0
 - Microsoft IIS 5.0

Impact: 
=========

NSFOCUS Security Team has found a exploited buffer overflow
vulnerability in 
a dynamic link library (perlIS.dll) of ActivePerl when handling overlong

filename. Exploit of it, an attacker could remotely execute arbitrary
code.

Description：
============

ActivePerl is a binary package of perl for Linux, Solaris or Windows
system 
developed by ActiveState. ActivePerl for windows has a dynamic link
library, 
perlIS.dll, which is a ISAPI extension to provide high-performance perl 
interface for Microsoft IIS server. 

PerlIS.dl was discovered to handle perl script request sent by user
without 
correct length check of the URL. In case that an attacker send an
overlong URL 
request, PerlIS would call strcpy() and copy it to a stack buffer, which
would 
trigger a buffer overflow. Attacker could overwrite some sensitive data
in the stack like returned address. With well-crafted URL request, the
attacker might 
be able to execute arbitrary code remotely.

Exploiting this vulnerability successfully, an attack might access 
IWAM_machinename account in IIS 5.0 and Local SYSTEM privilege in IIS 4.
0.


Exploit:
==========

$ lynx http://host/cgi-bin/`perl -e 'print "A" x 360'`.pl

The remote procedure call failed.

Workaround:
===================

Edit "perlIS.dll" ISAPI extension in Internet Service Manager and check
"Check 
that file exists" option.


Vendor Status:
==============

2001.10.15  We reported this vulnerability to ActiveState. 2001.10.23
ActiveState informed that the vulnerability has been eliminated in
            build 630.

Latest version of ActivePerl is available at

http://www.activestate.com/Products/ActivePerl/download.plex


Additional Information:
========================

The Common Vulnerabilities and Exposures (CVE) project has 
assigned the name CAN-2001-0815 to this issue. This is a 
candidate for inclusion in the CVE list (http://cve.mitre.org), which
standardizes names for security problems.  Candidates 
may change significantly before they become official CVE entries.

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==========
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Copyright 1999-2001 NSFOCUS. All Rights Reserved. Terms of use.


NSFOCUS Security Team <security@nsfocus.com>
NSFOCUS INFORMATION TECHNOLOGY CO.,LTD
(http://www.nsfocus.com)