Software Engineering Institute

RealFlex RealWin is SCADA server software that includes a Human Machine Interface (HMI) componant and runs on Microsoft Windows 2000 or XP. The demo version of RealWin contains a stack overflow in the way malicious "FC_INFOTAG/SET_CONTROL" packets are processed. According to Reversemode:

The bug is a classic stack overflow while processing a specially crafted FC_INFOTAG/SET_CONTROL packet. RealWin server accepts connections from FlewWin clients which use a propietary protocol. We can exploit this flaw from remote without having valid credentials.

Note that the non-demo version of RealWin has encryption protocol methods in place which calculate length of transmitted/received packets, preventing this buffer overflow.

This vulnerability could allow an unauthenticated, remote attacker to execute arbitrary code or cause a denial of service.

Update
RealFlex has made a fixed version of the demo software available to address this issue. See http://www.realflex.com/download/form.php for more information.

Restrict Access

Restrict network access to hosts that require connections to the demo version of RealWin. Do not allow access to RealWin from untrusted networks such as the internet.