 Fernando Gont has published an Internet-Draft describing how ICMP (Internet Control Message Protocol) can be exploited by malicious people to cause a DoS (Denial of Service). Cisco has acknowledged that various Cisco products are affected.
The published Internet-Draft details three types of attacks, which utilize the following ICMP messages to cause a negative impact on TCP connections either terminating or originating from a vulnerable device.
1) ICMP "hard" error messages 2) ICMP "fragmentation needed and Don't Fragment (DF) bit set" messages (known as PMTUD attacks) 3) ICMP "source quench" messages
These attacks can all be exploited to cause TCP connection resets, reduce the throughput in existing TCP connections, or consume large amounts of CPU and memory resources.
NOTE: See the original advisory for a list of affected versions.
OPERATING SYSTEM:
Cisco Content Services Switch 11000 Series (WebNS)
Cisco Global Site Selector (GSS) 4480 1.x
Cisco IOS 10.x
Cisco IOS 11.x
Cisco IOS 12.x
Cisco IOS R11.x
Cisco IOS R12.x
Cisco IOS XR (CRS-1) 3.x
Cisco ONS 15000 Series
Cisco PIX 6.x
Cisco SAN-OS 1.x (MDS 9000 Switches)
SOLUTION:
See patch matrix in vendor advisory for information about fixes.
http://www.cisco.com/warp/public/707/cisco-sa-20050412-icmp.shtml#software
PROVIDED AND/OR DISCOVERED BY:
Fernando Gont
ORIGINAL ADVISORY:
Cisco:
http://www.cisco.com/warp/public/707/cisco-sa-20050412-icmp.shtml
NISCC:
http://www.niscc.gov.uk/niscc/docs/al-20050412-00308.html
ICMP attacks against TCP:
http://www.gont.com.ar/drafts/icmp-attacks-against-tcp.html
VERIFY ADVISORY:
http://secunia.com/advisories/14904/
Secunia Security Advisories
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