Execution Flow

1) Explore

[Survey the application for user-controllable inputs] Using a browser, an automated tool or by inspecting the application, an adversary records all entry points to the application.

Technique

• Use a spidering tool to follow and record all links and analyze the web pages to find entry points. Make special note of any links that include parameters in the URL.
• Use a proxy tool to record all user input entry points visited during a manual traversal of the web application.
• Use a browser to manually explore the website and analyze how it is constructed. Many browsers' plugins are available to facilitate the analysis or automate the discovery.
• Manually inspect the application to find entry points.

2) Experiment

[Probe entry points to locate vulnerabilities] The adversary uses the entry points gathered in the "Explore" phase as a target list and injects postfix null byte(s) to observe how the application handles them as input. The adversary is looking for areas where user input is placed in the middle of a string, and the null byte causes the application to stop processing the string at the end of the user input.

Technique

• Try different encodings for null such as \0 or %00

3) Exploit

[Remove data after null byte(s)] After determined entry points that are vulnerable, the adversary places a null byte(s) such that they remove data after the null byte(s) in a way that is beneficial to them.

Technique

• If the input is a directory as part of a longer file path, add a null byte(s) at the end of the input to try to traverse to the given directory.

Prerequisites

Skills Required

Mitigations

Faiblesses connexes

References

REF-1

REF-445

REF-446

Submission

Modifications