The Terminal Services Advanced Client (TSAC) web control is an ActiveX control that can be used to run Terminal Services sessions within Internet Explorer. The downloadable ActiveX control provides nearly the same functionality as the full Terminal Services Client, but is designed to deliver this functionality over the Web.
A security vulnerability results because the control contains an unchecked buffer in the code that processes one of the input parameters. By calling the control on a client system and overrunning the buffer, an attacker could gain the ability to run code in the security context of the currently logged on user. This would enable the attacker to take any desired action on the user’s system. The attacker could mount an attack by either hosting a web page that exploits the vulnerability against any user who visits it, or by sending an HTML mail to another user.
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