UK pentester 'killa' claims $2K Bitcoin prize in PHP2Shell capture-the-flag contest

A UK-based developer and pentester has claimed a $2,000 Bitcoin prize for demonstrating the exploitability of the PHP2Shell vulnerabilities that melted the internet last week. Jaydip Modhwadia, 26, otherwise known as “Killa,” claimed the prize set by James Pavur, who launched the "Steal My Bitcoin" site on October 24. Pavur launched the CTF (capture the flag) challenge to prove that the PHP2Shell exploit was not as easy as those in the cybersecurity community claimed it to be, promising to award $2,000 in Bitcoin to anyone who could achieve Remote Code Execution (RCE) on his website. "My Bitcoin was stolen after 19.28 hours," the website now says, after Modhwadia claimed the prize, although the real time taken is thought to be less than three hours. Soon after Pavur launched the CTF on Saturday, prospective flag-catchers complained that the website he set up, which served only static HTML, was not built in a way that allowed the PHP2Shell exploit to achieve RCE. The web page was running a vulnerable version of PHP, but the exploit path required a vulnerable website to serve a PHP file for flag-catchers to use as a hook – something that Pavur seemingly updated at around 1300 UTC on October 25. Modhwadia achieved RCE on the website, exposing a PHP endpoint, at 1547 UTC. After an error from Pavur placing the wrong wallet key on the server, the CTF creator sent Modhwadia his award, which the community upped to $2,000 from Pavur’s initial $500. The pentester published a write-up of his method, a single-file Python script he says requires 20 HTTP requests "at most" to fully execute. Speaking to The Register , Modhwadia also confirmed that he got the flag in "around three or so hours in total." He said he followed the news about the competition, "but didn't attempt it until it gained significant notice." If he had attempted it before Pavur introduced the endpoint, he may have struggled. For hours, bug bounty hunters were trying to access the website to attempt the challenge, as news of the CTF had exploded across tech circles. "The fact that it took 19 hours was because after it went popular, the entire site became basically unusable for anyone at all," Modhwadia added. The challenge saw a huge number of attempts, despite Pavur's decision to introduce a prohibitive 1MB request limit on Nginx. Alon Gal, co-founder and CTO at Hudson Rock, commended Modhwadia's work, but added that his success achieved in just a few hours should not be taken to mean that the same …