Cisco VPN Client zero-length IKE packet payload denial of service
|cisco-vpn-zerolength-dos (9821)||Medium Risk|
The Cisco Virtual Private Network (VPN) Client software is vulnerable to a denial of service attack, caused by improper handling of specially-malformed packets. If a remote attacker sends a specially-crafted IKE packet with a zero-length payload to a vulnerable VPN Client, the attacker could cause the CPU usage to increase to 100%, which would cause a denial of service against the affected system.
Denial of Service
Upgrade to the latest version of Cisco VPN Client software (3.6 or later), as listed in Cisco Security Advisory: Cisco VPN Client Multiple Vulnerabilities. See References.
For FreeBSD Ports Collection:
Upgrade to the latest ports collection, as listed in FreeBSD Security Notice FreeBSD-SN-02:05. See References.
For OpenBSD 3.1:
Apply the patch for this vulnerability, as listed in OpenBSD 010: RELIABILITY FIX: July 5, 2002. See References.
For other distributions:
Contact your vendor for upgrade or patch information.
- Cisco Systems Inc. Security Advisory, 2002 August 12 UTC 1500: Cisco VPN Client Multiple Vulnerabilities.
- FreeBSD Security Notice FreeBSD-SN-02:05 : security issues in ports.
- OpenBSD 3.1 errata: 010: RELIABILITY FIX: July 5, 2002.
- BID-5440: Cisco VPN Client Zero Length IKE Packet Denial Of Service Vulnerability
- CVE-2002-0853: Cisco Virtual Private Network (VPN) Client 3.5.4 and earlier allows remote attackers to cause a denial of service (CPU consumption) via a packet with a zero-length payload.
- OSVDB ID: 15208: Cisco VPN Client Zero-Length Payload Packet DoS
- US-CERT VU#287771: Multiple vendors` Internet Key Exchange (IKE) implementations do not properly handle IKE response packets
- Cisco VPN Client 3.5.1
- Cisco VPN Client 3.5.2
Aug 12, 2002
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