8.6 Lab: Web shell upload via race condition

A Simple writeup is posted on Medium - Medium: cyberw1ng

Disclaimer:

The content shared in this video is intended for educational purposes only. The demonstrations, tutorials, and information presented are meant to highlight common vulnerabilities in cybersecurity systems and are performed in controlled environments, such as the Portswigger Labs, with explicit permission. The primary goal is to enhance knowledge and awareness of potential security threats and vulnerabilities.

Please be aware that attempting to exploit or replicate these techniques without proper authorization may violate applicable laws and regulations. The creator of this content does not encourage any illegal activities, and the responsibility for any misuse or consequences arising from these demonstrations lies solely with the viewer.

Always ensure that you have the appropriate permissions before conducting security testing on any system. It is recommended to seek professional advice and authorization from the relevant parties before attempting any penetration testing, ethical hacking, or security research.

The creator disclaims any liability for the misuse or misinterpretation of the information provided in this video. Viewers are encouraged to use this knowledge responsibly and ethically.

Description - Portswigger Lab
This lab contains a vulnerable image upload function. Although it performs robust validation on any files that are uploaded, it is possible to bypass this validation entirely by exploiting a race condition in the way it processes them. To solve the lab, upload a basic PHP web shell, then use it to exfiltrate the contents of the file /home/carlos/secret. Submit this secret using the button provided in the lab banner | Karthikeyan Nagaraj

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