**nul byte injection**. This consists of sending a type of file with the name e.g. `test.html%00.jpg` to a server in order to exploit a vulnerability in it. The aim of this attack is to trick the server into interpreting the file differently than it should, which can result in various forms of exploitation. ## <br>How it works - **Nul Byte (`%00`)**: On many systems, the null byte (`%00` in URL encoding) is interpreted as the end of a string. When used in a filename, it can cause unexpected behavior. - **Attacker intent**: The attacker may try to get the server to treat the file as a different type than it appears. For example, `test.html%00.jpg` can be interpreted as `test.html` in certain contexts, leading the server to treat the file as HTML instead of an image, which can be used to execute malicious code. Common Exploits: 1. **Upload Filter Bypass**: If the server is configured to accept only certain types of files (e.g. `.jpg`), but fails to process the `%00` correctly, it may accept a malicious file with an `.html` or `.php` extension, allowing scripts to be executed on the server. 2. **Arbitrary Code Execution**: The attacker may be able to upload a malicious script disguised as an image or other permitted file type and then execute this script, compromising the server. We have already listed many other attacks here on our website, which is why we encourage everyone to be vigilant and always take serious precautionary measures. Let us know in the comments if you've experienced a hacker attack and how you got rid of it.