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Rule:
--
Sid:
100000160
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Summary:
This event is generated when an abnormally larger number of packets are
received from a single source by an SIP-enabled host in a short period of time.
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Impact:
This can be an indication of a denial of service attack in progress.
--
Detailed Information:
This rule is designed to detect overly large amounts of traffic coming from a
single host to the SIP port on an internal host, as it is possible to cause a
denial of service by sending a large number of packets with invalid data.
--
Affected Systems:
Any which implement the SIP protocol.
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Attack Scenarios:
An attacker could use a script to flood a system with invalid messages, causing
a denial of service.
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Ease of Attack:
Simple, as it is trivial to write a script to generate random data.
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False Positives:
Known SIP proxies may receive a high volume of legitimate data, and NAT devices
may appear to be sending a larger amount of data than a regular host. It is
recommended that users whitelist known SIP proxies and NAT devices.
--
False Negatives:
None known.
--
Corrective Action:
Use a firewall or other access-restriction device to block unwanted messages at
your network's border.
--
Contributors:
Jiri Markl <jiri.markl@nextsoft.cz>
Sourcefire Research Team
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Additional References
Other:
--
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