The Microsoft Remote Access Service API contains a vulnerability that allows local attackers to execute arbitrary code with system privileges.
The Microsoft Remote Access Service (RAS) Application Programming Interface (API) allows Windows programs to make dial-up connections to remote servers. There is a buffer overflow in the RAS API that allows an attacker to execute arbitrary code with LocalSystem privileges. To exploit this vulnerability, the attacker must log into an account on the affected system and create a RAS phonebook entry. When any program attempts to use the RAS API to parse the malicious phonebook entry, the entry will cause a buffer overflow and allow the attacker to execute arbitrary code.
Once the malicious phonebook entry has been created, the attacker may exploit the vulnerability by initiating a remote connection. However, the attacker may also choose to delay exploitation and allow a different, unsuspecting user to exploit the vulnerability on the attacker's behalf. Since any attempt by the RAS API to parse the phonebook entry may trigger this vulnerability, the victim user need not even attempt to make a connection. The victim might trigger the vulnerability by simply viewing the properties of the crafted phonebook entry.
Attackers who are able to create malicious RAS phonebook entries can execute arbitrary code with LocalSystem privileges. In some cases, failed attempts to exploit this vulnerability will cause the affected host to crash.
Apply a patch from your vendor
Prevent users from accessing the Remote Access Service
This vulnerability was discovered by Mnemonix (aka David Litchfield).
This document was written by Jeffrey P. Lanza and is based on information provided by Microsoft and David Litchfield.
|Date First Published:||2002-06-13|
|Date Last Updated:||2002-06-25 20:33 UTC|