Nortel CS1000 Communications Server Remote Denial of Service Vulnerability

April 20th, 2011
ZDI-11-141 ZDI-CAN-950

CVE ID

CVSS Score

10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

Affected Vendors

Nortel

Affected Products

CS1000 Communications Server

Vulnerability Details

This vulnerability allows remote attackers to create a denial of service condition on vulnerable installations of Nortel CS1000 Communication Server. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the process listening on UDP port 5100. When parsing a request, it takes the size and subtracts 2. This can be abused to cause the integer to wrap negatively and subsequently cause the process to crash while copying memory. This can be abused by a remote attacker to crash the PBX server.

Additional Details

Nortel has issued an update to correct this vulnerability. More details can be found at:
https://support.avaya.com/css/P8/documents/100133768

Disclosure Timeline

  • 2010-09-24 - Vulnerability reported to vendor
  • 2011-04-20 - Coordinated public release of advisory

Credit

Anonymous

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