Positive Technologies Security Advisory http://www.ptsecurity.com Title: DoS-attack in Kerio WinRoute Firewall Date: March, 07 2003 Severity: High Application: Kerio WinRoute Firewall 5.0.1 Platform: Windows 95/98/ME/NT/2000/XP Vendor Status: Notified, patched in version 5.0.2 I. DESCRIPTION --------------- Denial of Service condition exists in Kerio WinRoute Firewall's Web administration interface which hand service with 100% CPU utilization. Positive Technologies reports that single simple HTTP request to Kerio Winroute Firewall Web administration interface (TCP/4080) GET / HTTP/1.0 Authorization: Basic XXX instead of correct one: GET / HTTP/1.0 Host: server Authorization: Basic XXX causes 100% CPU utilization of attacked computer. II. IMPACT --------------- Remote user can launch denial of service attack against web interface (port TCP/4080). Single request causes 100% CPU utilization. As a result more than 50% of future connection requests may be lost disturbing normal functionality of the networking services. III. SOLUTION --------------- Block TCP/4080 access or upgrade to Kerio WinRoute Firewall 5.0.2. IV. VENDOR FIX/RESPONSE --------------- Vendor was notified on 10.03.2003. V. CREDIT --------------- Positive Technologies is information security company especially focused on protection of corporate networks from external attacks. The main trend of PT’s activity is computer networks security audit and service. PT offers wide range of services in the filed of information security: from network architecture development or optimization to consulting and custom software source-code examination.