Top Layer Attack Mitigator IPS 5500 Denial of Service
Top Layer Attack Mitigator IPS 5500 Denial of Service
Problem discovered: July 22nd 2004
Vendor contacted: July 23rd 2004
Advisory published: August 25th 2004
Abstract:
Top Layer's Attack Mitigator IPS 5500 is an ASIC-based Network Intrusion
Prevention System (NIPS), with blocking and control capabilities against certain
types of cyber attacks. The product's datasheet states that 'Top Layer's
second-generation ASIC technology and patented algorithms integrate proven
stateful analysis techniques with its new ' TopInspect ' deep packet inspection
technology and industry-leading DoS attack protection to provide comprehensive
protection from Internet-based and internal threats'.
During a recent security consultancy engagement, IRM discovered that under
certain specific circumstances the Top Layer IPS 5500 series CPU usage could
reach 100% utilisation , where it would not be able to process further network
traffic, and any site protected by the device would become inaccessible.
Description:
The system under test comprised a web server farm accessible via a load balancer
and protected by an IPS 5500 device. IRM discovered that upon simulating more
than 2000 concurrent HTTP requests to the server farm, the IPS 5500 device
reached a state where it was utilising all its CPU power and therefore was
unable to process standard HTTP traffic.
Tested Versions:
Top Layer Attack Mitigator IPS 5500 running software version 3.11.008
Vendor Response:
Top Layer was notified of this issue on July 22, 2004 by IRM. A bug exists in
Attack Mitigator IPS 5500 software versions earlier than V3.11.014 that could
cause the IPS 5500 device to incorrectly enter an overload protection mode and
negatively impact network traffic. In extreme cases, this can cause a denial of
service condition. The effect of this bug appears only when the IPS 5500 unit is
configured in a topology where a high-volume of network packets traverse the IPS
unit twice due to a "one-armed" routing configuration.
The presence of this error condition will exhibit the following when viewing the
IPS5500 Immediate Security Report: Current System Processor Utilization = 100%
and the value for System CPU Overload Protection is non-zero.
Vendor & Patch Information:
Top Layer were contacted during the testing and immediately started
investigating the issue. Top Layer then updated the IPS code (to version
3.11.014) which resolved the issue during the timescales of the security
engagement. The latest IPS 5500 software is available from Top Layer at:
http://www.toplayer.com/content/support/tech_assist/index.jsp
Workarounds:
Top Layer explained that a workaround would be to avoid deploying an IPS 5500 in
"one-armed" router configurations.
Credits:
Research & Advisory: M Faour, L Garman
Disclaimer:
All information in this advisory is provided on an 'as is' basis in the hope
that it will be useful. Information Risk Management Plc is not responsible for
any risks or occurrences caused by the application of this information.