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Low Severity
Definition ID 15, Last Updated Jan 04th 2011, 12:22 a.m. (Revision 2)


Detects NOOP sleds in JavaScript; these indicate the presence of potentially malicious JavaScript code.


The definition detects NOOP (no operation) sleds in JavaScript. NOOP sleds are used as part of buffer overflow attacks and are commonly observed in client-side attacks.

False Positives

This definition may generate a false positive on sites that use escaped characters to represents non-ASCII characters. This type of false positive is fairly rare though since this definition only triggers if two or more NOOPs are observed.

Definition Code