Title: Kerio Personal Firewall IP Options Denial Of Service Vulnerability
Severity: HIGH
Description:
Kerio Personal Firewall (KPF) is a desktop firewall solution that performs stateful packet inspection. It is commercially available for the Microsoft Windows platform.
A remote denial of service vulnerability affects the IP options filtering functionality of Kerio's Personal Firewall. This issue is caused by a failure of the application to properly handle malformed network packets.
The problem presents itself when a malformed packet is received by the affected firewall. Apparently a packet with an IP option that has a specified length of zero will cause the vulnerable application to loop indefinitely, causing the affected computer to require a hard restart to return to a functional state.
Specifically this issue is triggered as the algorithm used to parse the IP options of a packet header employs the specified size of the option to increment to the next IP option in the header. If this IP option size is reported to be of zero length then the application will attempt to parse the same IP option indefinitely.
A remote attacker can exploit this issue anonymously with a spoofed packet to cause a computer running the affected application to hang indefinitely, denying service to legitimate users.
Affected Products:
- Kerio Personal Firewall 4.0.10
- Kerio Personal Firewall 4.0.16
- Kerio Personal Firewall 4.0.6
- Kerio Personal Firewall 4.0.7
- Kerio Personal Firewall 4.0.8
- Kerio Personal Firewall 4.0.9
- Kerio Personal Firewall 4.1.0
- Kerio Personal Firewall 4.1.1
References:
- Kerio: KSEC-2004-11-04-01 - Malicious packet can cause 100% utilization and freeze
- Kerio: Kerio Home Page
- Kerio: Personal Firewall Download Page
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