What is signature-based detection?

Signature-based detection is a style of detection that provides a mechanism for how the detector scans the data to find attacks. In this style of detection, unique identifiers are generated about a known attack so that any attack of that kind is rapidly dealt with.

Implementation

In signature-based detection, the detector flags any activity that matches the structure of a known attack. It is like blacklisting the attacks. It keeps a list of patterns that are not allowed and alerts if it sees something that matches the attacks in the list.

Signature-based detection

Example

An example of signature-based detection can be buffer overflows. Since buffer overflows usually contain shellcodescode that starts the command shell prompt, the strategy is to keep a list of common shellcodes and alert if any request contains a shellcode. Similarly, SNORT is also a detection software that follows a signature-based style.

The following shows how SNORT works:

Signature-based detection working

However, signature-based detection does not come without tradeoffs. The following table shows the benefits and drawbacks of signature-based detection:

Benefits and drawbacks of signature-based detection

Benefits

Drawbacks

It is conceptually simple.

It would not catch new attacks without a known signature.

It is good at detecting known attacks.

It might not catch variants of known attacks if the variant does not match the signature.

It is easy to share signatures and build up shared libraries of attacks.

The attacker can modify their attack to avoid matching the signatures and can still attack.

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