Microsoft Outlook Express And Windows Mail NNTP Protocol Heap Buffer Overflow Vulnerability



Date Discovered

October 9, 2007


Microsoft Outlook Express and Windows Mail are prone to a remote heap-based buffer-overflow vulnerability. This issue occurs because the applications fail to perform adequate boundary-checks on user-supplied data. Successfully exploiting this issue will allow an attacker to execute arbitrary code with the privileges of the currently logged-in user.

Technologies Affected

  • HP Storage Management Appliance 2.1
  • HP Storage Management Appliance I
  • HP Storage Management Appliance II
  • HP Storage Management Appliance III
  • Microsoft Outlook Express 5.5 SP2
  • Microsoft Outlook Express 6.0
  • Microsoft Outlook Express 6.0 SP1
  • Microsoft Windows Mail
  • Nortel Networks Centrex IP Client Manager
  • Nortel Networks Centrex IP Element Manager
  • Nortel Networks Circuit Switching
  • Nortel Networks Integrated Access - Cable
  • Nortel Networks Packet Transit - IP
  • Nortel Networks Universal Access - IP


Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of anomalous or suspicious activity. This includes but is not limited to requests that include NOP sleds and unexplained incoming and outgoing traffic. This may indicate exploit attempts or activity that results from successful exploits.

Do not accept or execute files from untrusted or unknown sources.
Users should exercise caution when displaying email messages provided by an unknown or untrusted source.

Do not follow links provided by unknown or untrusted sources.
Attackers could exploit this vulnerability by enticing a user to visit a malicious website. Do not follow links provided by sources of questionable integrity.

Implement multiple redundant layers of security.
Memory-protection schemes such as nonexecutable stack and heap configurations and randomly mapped memory segments will complicate exploit of memory-corruption vulnerabilities.

When possible, limit the privileges granted to users to the least amount required.
To reduce the impact of latent vulnerabilities, limit user privileges to the least amount possible. This can help prevent privileged functions from running.

The vendor has released an advisory to address this issue in supported versions of affected applications. Please see the referenced advisory for details on obtaining and applying the appropriate updates. NOTE: Microsoft has released a revised bulletin (V2.0) MS07-056 to include Windows XP Professional x64 Edition in the affected software section and to address missing information for Outlook Express 6.0 SP1 on Windows 2000 SP4 and for Outlook Express 5.5 SP2 on Windows 2000 SP4.



Greg MacManus of VeriSign iDefense Labs is credited with the discovery of this vulnerability.

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