Clavister Information for VU#464113
TCP/IP implementations handle unusual flag combinations inconsistently
- Vendor Information Help Date Notified:
- Statement Date: 21 Mar 2003
- Date Updated: 01 Apr 2003
Clavister Firewall: Not vulnerable.
Clavister Firewall only allows plain SYN packets to create new states, and, as such, also protects hosts behind it.
In addition, thorough packet scrubbing is performed. The default settings for packets where the SYN flag is set are:
SYN+URG: Drop and log the packet
SYN+RST: Drop and log the packet
SYN+FIN: Drop and log the packet
SYN+PSH: Strip the PSH flag and log
Although SYN+PSH is very uncommon, some TCP stacks have been observed to use them. Early versions of MacTCP is one such stack.
We are not aware of further vendor information regarding this vulnerability.
The CERT/CC has no additional comments at this time.
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