FLIRT Signatures Evasion

Created the Friday 01 July 2022. Updated 9 months, 3 weeks ago.

FLIRT Signature evasion is a technique used by malware to hide malicious code inside legitimate functions from known libraries. FLIRT (Fast Library Identification and Recognition Technology) is a database that contains signature patterns for identifying known functions from legitimate libraries.

Malware authors can abuse these signatures by modifying or adding specific bytes to the code, so that it appears to be a legitimate function when scanned by a FLIRT database. This can trick reverse engineering tools that rely on FLIRT signatures without performing further analysis, and make it more difficult for security analysts to identify and analyze the malware.

By using this technique, malware authors can evade detection and make their code more difficult to understand and analyze.

Featured Windows API's

Below, you will find a list of the most commonly used Windows API's that are currently utilized by malware authors for current evasion technique. This list is meant to provide an overview of the API's that are commonly used for this purpose. If there are any API's that you feel should be included on this list, please do not hesitate to contact us. We will be happy to update the list and provide any additional information or documentation that may be helpful.

Code Snippets

Additional Resources

External Links

The resources provided below are associated links that will give you even more detailed information and research on current evasion technique. It is important to note that, while these resources may be helpful, it is important to exercise caution when following external links. As always, be careful when clicking on links from unknown sources, as they may lead to malicious content.

Subscribe to our Newsletter

The information entered into this form is mandatory. It will be subjected to computer processing. It is processed by computer in order to support our users and readers. The recipients of the data will be :

According to the Data Protection Act of January 6th, 1978, you have at any time, a right of access to and rectification of all of your personal data. If you wish to exercise this right and gain access to your personal data, please write to Thomas Roccia at

You may also oppose, for legitimate reasons, the processing of your personal data.