[NT] CheckMark MultiLedger Buffer Overflow Vulnerability (DUNZIP32.dll)

Type securityvulns
Reporter Securityvulns
Modified 2005-10-31T00:00:00


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CheckMark MultiLedger Buffer Overflow Vulnerability (DUNZIP32.dll)


<http://www.checkmark.com/> 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.


Vulnerable Systems: * CheckMark MultiLedger version 6.0.3. Other versions may also be affected. * DynaZip library version (According to InnerMedia version 5.00.03 and prior are affected)

Related advisories: <http://www.securiteam.com/windowsntfocus/6U00D0UBGI.html> 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> 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> 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


The information has been provided by <mailto:juha-matti.laurio@netti.fi> Juha-Matti Laurio. The original and article can be found at: <http://www.networksecurity.fi/advisories/multiledger.html> http://www.networksecurity.fi/advisories/multiledger.html


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