How can an attacker disguise his buffer overflow attack signature such that there is a greater probability of his attack going undetected by the IDS?

Basically, there are two approaches to network intrusion detection: signature detection, and anomaly detection. The signature detection approach utilizes well-known signatures for network traffic to identify potentially malicious traffic. The anomaly detection approach utilizes a previous history of network traffic to search for patterns that are abnormal, which would indicate an intrusion. How can an attacker disguise his buffer overflow attack signature such that there is a greater probability of his attack going undetected by the IDS?

A.
He can chain NOOP instructions into a NOOP "sled" that advances the processor’s instruction pointer to a random place of choice

B.
He can use polymorphic shellcode ?with a tool such as ADMmutate – to change the signature of his exploit as seen by a network IDS

C.
He can use a dynamic return address to overwrite the correct value in the target machine’s computer memory

D.
He can use a shellcode that will perform a reverse telnet back to his machine

Explanation:

ADMmutate is using a polymorphic technique designed to circumvent certain forms of signature based intrusion detection. All network based remote buffer overflow exploits have similarities in how they function. ADMmutate has the ability to emulate the protocol of the service the attacker is attempting to exploit. The data payload (sometimes referred to as an egg) contains the instructions the attacker wants to execute on the target machine. These eggs are generally interchangeable and can be utilized in many different buffer overflow exploits. ADMmutate uses several techniques to randomize the contents of the egg in any given buffer overflow exploit. This randomization effectively changes the content or ‘signature’ of the exploit without changing the functionality of the exploit.