Signature Detail
Short Name |
TCP:C2S:EXPLOIT:URG-WO-FLG |
|---|---|
Severity |
Medium |
Recommended |
No |
Category |
TCP |
Release Date |
2003/04/22 |
Update Number |
1213 |
Supported Platforms |
idp-4.0+, isg-3.0+, j-series-9.5+, mx-9.4+, srx-9.2+, srx-branch-9.4+, vsrx-12.1+ |
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.
References