On April 15, 2025, the controversial imageboard 4chan experienced a significant security breach that exposed sensitive internal data, including source code, moderator information, and administrative tools. The attackers have since disclosed the sophisticated exploit method they used to infiltrate the platform’s backend systems.
Exploit Methodology
Contrary to initial speculation, the breach did not involve SQL injection techniques. Instead, the attackers exploited a vulnerability in 4chan’s file validation system. Specifically, they targeted how the platform processes uploaded files on certain boards, including /g/, /pol/, /qst/, /sci/, and /lg/. The attackers noted that 4chan failed to verify that uploaded files were legitimate PDFs. This oversight allowed them to upload PostScript files containing malicious drawing commands disguised as PDFs.
These malicious files were processed by Ghostscript, a software used by 4chan to generate thumbnail images. Notably, 4chan was using a severely outdated version of Ghostscript from 2012, which contained known vulnerabilities. By exploiting these vulnerabilities, the attackers gained an initial foothold in the system. They then leveraged a misconfigured suid binary to escalate their privileges to that of the global user, effectively gaining complete control over the server.
Extent of the Breach
The attackers claim to have maintained access to 4chan’s systems for over a year before executing the attack. During this period, they extracted the platform’s PHP source code, including the main file yotsuba.php, which manages posting and reporting functions. Additionally, they accessed the email addresses and contact information of approximately 218 moderators, administrators, and janitors (lower-level moderators).
As proof of their control over the system, the attackers temporarily restored a previously banned board called /qa/ and defaced it with the message U GOT HACKED XD. This action confirmed their administrative privileges within the system.
Attribution and Motives
A group associated with the rival imageboard Soyjak Party (colloquially known as Sharty) has claimed responsibility for the attack. In a post on their platform, they stated: Today, April 14, 2025, a hacker, who has been in 4cuck’s system for over a year, executed the true operation soyclipse.
Security Implications
Security researchers have highlighted that 4chan’s outdated technical infrastructure made it particularly vulnerable to such attacks. The platform was reportedly using an extremely out-of-date version of PHP with numerous vulnerabilities and deprecated functions to interact with its MySQL database.
The breach has raised serious concerns about user privacy. While 4chan provides its users with anonymity, the site collects IP addresses. With admin panels compromised, unauthorized parties could access this data, potentially de-anonymizing users.
Current Status
As of this writing, 4chan remains only intermittently accessible as administrators work to mitigate the damage. The exposure of moderator emails has also compromised the anonymity that 4chan has long promised, with some leaked addresses reportedly including .edu and .gov domains.
