TCP: C2S Evasion SYN in ESTABLISHED State
This protocol anomaly triggers when it detects a SYN packet while a flow is in the ESTABLISHED state. Because IDP can determine what the receiving host will do with these abnormal packets, it is safe to permit them.
Extended Description
A TCP packet that has the SYN flag set after the initial SYN packet has been transmitted during a connection session constitutes a protocol anomaly. The detection of this condition could indicate a network configuration error, or that malicious activity involving the injection of malformed IP packets is underway.
References
Short Name
TCP:C2S:EVASION:C2S-ESTB-SYN
Severity
Minor
Recommended
False
Recommended Action
None
Category
TCP
Release Date
08/27/2003
Supported Platforms
mx-19.3
vmx-19.3
vsrx-19.2
srx-19.3
srx-branch-19.3
vsrx3bsd-19.2
srx-19.4
vsrx3bsd-19.4
srx-branch-19.4
vsrx-19.4
vmx-19.4
mx-19.4
srxevo-25.4
vsrx-26.2
srx-26.2
srx-branch-26.2
vsrx3bsd-26.2
mx-12.3
srx-12.3
srx-branch-12.3
vsrx-12.3
Sigpack Version
3324
False Positive
Unknown