TCP: S2C Flags Error Additional Flags in SYNACK Packet

This protocol anomaly triggers when it detects a SYN-ACK packet with unexpected flags set. This can be a SYN-ACK-FIN packet attempting to hang the server.

Extended Description

An attacker could maliciously craft a packet containing an invalid combination of SYN, FIN, ACK, PSH, and URG bits, sent from a server to a client. Such a packet is abnormal. Detection of this packet could indicate a network misconfiguration or that an attacker is attempting to insert malformed TCP packets into the network.

References

URL: http://www.faqs.org/rfcs/rfc1180.html

Short Name

TCP:S2C:FLAGSERROR:DIR-SYNACK

Severity

Major

Recommended

False

Recommended Action

Drop Packet

TCP: S2C Flags Error Additional Flags in SYNACK Packet

Extended Description

References

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