TCP: Urgent Data Without Flags
This protocol anomaly triggers when it detects a TCP packet with the Urgent Pointer set, but the URG flag in the TCP header is not set. Because TCP/IP stacks differ in how they handle such packets, this can be an evasion attempt.
Extended Description
If a packet is detected in which the URGENT POINTER contains a value, but the URG flag is not set, this constitutes a protocol anomaly. This condition may be the result of a network configuration error, or that malicious activity involving transmission of malformed TCP/IP datagrams is underway.
Short Name
TCP:C2S:EXPLOIT:URG-WO-FLG
Severity
Minor
Recommended
False
Recommended Action
None
Category
TCP
Release Date
04/22/2003
Supported Platforms
srx-branch-12.3
srx-19.3
srx-branch-19.3
vsrx3bsd-19.2
srx-branch-19.4
vsrx-19.4
mx-12.3
mx-19.4
vmx-19.4
mx-19.3
vsrx3bsd-19.4
srx-19.4
vsrx-12.3
vmx-19.3
vsrx-19.2
srx-12.3
Sigpack Version
3324
False Positive
Unknown