'Highly critical' Citrix Presentation Server Client flaw reported

By Frank Washkuch on Mar 9, 2007 1:16AM

A vulnerability in Citrix Presentation Server Client that can be exploited by attackers to compromise a PC was reported this week.

The flaw is caused by an unspecified error within support for ICA connections when using a proxy server, according to an advisory from Secunia. An attacker can exploit the flaw to execute arbitrary code onto a victimised system.

Secunia urged users this week to upgrade to Citrix Presentation Server Client version 10 or later.

The Denmark-based vulnerability monitoring firm ranked the flaw as "highly critical," meaning it can be exploited by a remote user with arbitrary code.

An attacker can exploit the flaw by duping a user into visiting a specially crafted web page, according to an advisory from US-CERT.

Citrix said in an advisory released Tuesday that the flaw is present in versions 9.230 and earlier. Florida based vendor ranked the vulnerability as "high" danger and said that it is "likely to be exploitable in most client deployments."

A Citrix official could not immediately be reached for comment today.

A different flaw in Presentation Server Client was discovered late last year, this one cause by a boundary error within the SendChannelData() method in the ICA Client ActiveX control component that could lead to buffer overflow.

Citrix advised users to upgrade to versions 9.230 to correct that flaw, according to a Secunia advisory.