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CheckMark MultiLedger Buffer Overflow Vulnerability (DUNZIP32.dll)

SUMMARY

<http://www.checkmark.com/&gt; CheckMarkMultiLedger - "A proven integrated,
networkable financial package for small businesses, MultiLedger is easy to
use and installs quickly".

CheckMark MultiLedger accounting system for Windows is confirmed to be
affected to a buffer overflow vulnerability due to its usage of a
third-party DLL called DUNZIP32.dll.

DETAILS

Vulnerable Systems:

• CheckMark MultiLedger version 6.0.3. Other versions may also be
  affected.
• DynaZip library version 3.0.0.14 (According to InnerMedia version
  5.00.03 and prior are affected)

Related advisories:
<http://www.securiteam.com/windowsntfocus/6U00D0UBGI.html&gt; Windows Shell
ZIP File Decompression DUNZIP32.DLL Buffer Overflow

The vulnerability is caused due to a boundary error in a 3rd-party
compression library's (DUNZIP32.dll) old, vulnerable version used in
company data restore functions. This can be exploited to cause a buffer
overflow via a specially crafted company backup file. When a specially
crafted .zip backup file containing a file with an overly long filename (a
file name or files inside a ZIP) is opened, the payroll application will
crash and the attacker may be able to execute arbitrary code on user's
system.

Vendor Status:
An updated software version 7.0.2 is available from vendor:
<http://www.checkmark.com/support/patch_win_ml.php&gt;
http://www.checkmark.com/support/patch_win_ml.php
"Installation Instructions: You need at least version 7.0 of MultiLedger
for Windows in order to run this patch."

Software Updates for Registered Users:
<http://www.checkmark.com/order/updates.php&gt;
http://www.checkmark.com/order/updates.php

Workaround:
As a workaround, Dunzip32.dll library can be deleted or renamed, or
un-registered with the Windows "Regsvr32 /u" command.
NOTE: This method breaks application's Backup and Restore functions and is
not recommended.

Disclosure Timeline:

• 24-Jan-2005 - Vulnerability researched and confirmed
• 24-Jan-2005 - Vendor was contacted, workarounds delivered to the vendor
• 24-Jan-2005 - (Vendor's reply to CheckMark Payroll for Windows
  vulnerability)
• 04-Mar-2005 - Vendor informed about upcoming, fixed version
• 11-Oct-2005 - Detailed research
• 26-Oct-2005 - Vendor was contacted again
• 26-Oct-2005 - Vendor's reply, vulnerability is fixed
• 28-Oct-2005 - Security companies and several CERT units contacted

ADDITIONAL INFORMATION

The information has been provided by <mailto:[email protected]>
Juha-Matti Laurio.
The original and article can be found at:
<http://www.networksecurity.fi/advisories/multiledger.html&gt;
http://www.networksecurity.fi/advisories/multiledger.html

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