Software Engineering Institute

Ethereal is a network traffic analysis package. It includes the ability to decode packets containing PGM data. There is a vulnerability in the way the PGM protocol dissector parses PGM data containing a crafted NAK list.

According to the e-matters Security Advisory:

"When parsing an PGM packet with a carefully crafted NakList a possible integer underflow can result in a very small stack-overflow. Due to the stacklayout code execution exploitation seems very unlikely."

A remote, unauthenticated attacker could cause Ethereal to crash or possibly execute arbitrary code on the vulnerable system.

Upgrade

Upgrade to version 0.10.3 or later.

Note: Ethereal is considered BETA software at this time.

Disable Dissector

If you are unable to upgrade to version 0.10.3 or later, you can disable the PGM protocol dissector by performing the following actions in Ethereal:

(for Ethereal versions 0.8.x and 0.9.x)
1) Select Edit->Protocols
2) Deselect the PGM protocol dissector from the list

(for Ethereal versions 0.10.x)
1) Select Analyze->Enabled Protocols
2) Disable the PGM protocol dissector from the list by unchecking its "Status" checkbox