Signature Detail
Short Name |
TCP:S2C:EVASION:S2C-URG-OUT-WIN |
|---|---|
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: S2C Evasion Urgent Data Out of Window
This protocol anomaly triggers when it detects a TCP packet with urgent data, but the data is not in the receiver window. 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 URG flag is set, but the data is not in the receiver window, this constitutes a protocol anomaly. This condition may be the result of a network configuration error. It could also indicate that malicious activity involving transmission of malformed TCP/IP datagrams is underway.
References