Clavister Information for VU#464113

TCP/IP implementations handle unusual flag combinations inconsistently


Not Affected

Vendor Statement

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.

Vendor Information

We are not aware of further vendor information regarding this vulnerability.

Vendor References



The CERT/CC has no additional comments at this time.

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