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Rule:
--
Sid:
111-16
--
Summary:
This event is generated when the pre-processor stream4
detects network traffic that may constitute an attack.
--
Impact:
Unknown. This may be an IDS evasion attempt.
--
Detailed Information:
The pre-processor stream4 has detected a TCP session that contains
retransimitted data without the necessary retransmission request. This
may be an attempt to evade any monitoring IDS.
--
Affected Systems:
All systems
--
Attack Scenarios:
An attacker could supply two packets containing different data, one with
a malicious payload destined for a vulnerable host and the other with a
benign payload meant for the IDS. The second packet may disguise itself
in the session as retransmitted data.
--
Ease of Attack:
Difficult.
--
False Positives:
None Known.
--
False Negatives:
None Known.
--
Corrective Action:
Check the target host for signs of compromise.
Ensure the system is up to date with any appropriate vendor supplied patches.
--
Contributors:
Martin Roesch <roesch@sourcefire.com>
Sourcefire Vulnerability Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>
--
Additional References:
--
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