>>41343
>>41677
>>42036

Yes, the scenario you described is technically possible, based on the components involved and known security vulnerabilities. Below, I’ll break down each part of your query and explain why this exploit chain could plausibly work, along with some caveats.
1. PDF Uploads on 4chan
You stated that 4chan allows PDF uploads on specific boards like /gd/ (graphic design), /po/ (papercraft), /qst/ (quests), /sci/ (science), and /tg/ (tabletop games). While I don’t have direct evidence from 4chan’s documentation to confirm this, it’s plausible. Many imageboards and forums permit file uploads beyond just images, including PDFs, especially on boards where such files are relevant (e.g., design files on /gd/ or printable game assets on /tg/). This assumption aligns with typical functionality of user-driven platforms, so this step holds up.
2. Lack of File Verification
You claim that 4chan doesn’t verify whether an uploaded file with a .pdf extension is actually a PDF, allowing other formats like PostScript to be uploaded. This is a common vulnerability in file upload systems. Many platforms rely on file extensions rather than inspecting the file’s contents or MIME type, which can be bypassed by renaming a PostScript file (e.g., malicious.ps) to malicious.pdf. If 4chan indeed skips proper validation, a PostScript file could be uploaded under the guise of a PDF. This is technically feasible and a realistic oversight.
3. PostScript Files Processed by Ghostscript
You suggest that the uploaded PostScript file is passed to Ghostscript to generate a thumbnail image. This is a reasonable assumption. Ghostscript is a widely used interpreter for both PostScript and PDF files, commonly employed by web applications to process uploaded files and create previews or thumbnails. PostScript files contain drawing commands that Ghostscript can render into images, so if 4chan uses Ghostscript for thumbnail generation, it would naturally process such a file. This step is consistent with standard web server workflows.
4. Vulnerable Ghostscript Version from 2012
You specify that 4chan uses a 2012 version of Ghostscript, which you describe as “trivial to exploit.” Older software versions often harbor known vulnerabilities, and Ghostscript is no exception. Around 2012, Ghostscript had vulnerabilities that could be exploited via malicious PostScript or PDF files. For example:
Sandbox bypass vulnerabilities: PostScript’s sandboxing mechanisms could be circumvented, allowing malicious code to execute.

Code execution bugs: Historical reports confirm that Ghostscript had flaws enabling arbitrary code execution, especially when processing untrusted input like uploaded files.

While I can’t verify the exact version 4chan uses, a 2012 version would likely predate many security patches, making it susceptible to known exploits. If a malicious PostScript file triggers such a vulnerability, it could execute arbitrary code on the server. This part of the scenario is technically plausible.
5. Exploiting a SUID Binary for Privilege Escalation
The final step involves exploiting a “mistaken SUID binary” to elevate privileges to the “global user” (likely root). Here’s why this could work:
What is a SUID binary? A Set-User-ID (SUID) binary runs with the permissions of its owner, often root, rather than the user executing it. If a SUID binary is misconfigured or vulnerable (e.g., to buffer overflows), it can be exploited to execute commands with elevated privileges.

Feasibility: If the attacker gains code execution via Ghostscript, they could then target a vulnerable SUID binary on the system. For instance, running a crafted command or script could leverage the SUID binary’s privileges to spawn a root shell.

This step depends on the presence of a vulnerable SUID binary, but such misconfigurations are not uncommon, especially on older or poorly maintained systems. Resources on privilege escalation consistently highlight SUID exploits as a viable technique, so this is technically possible.
The Exploit Chain
Here’s how it all ties together:
Upload a malicious PostScript file disguised as a PDF to a 4chan board (e.g., /gd/).

4chan’s server, lacking proper file verification, accepts the file.

The file is processed by a 2012 version of Ghostscript to generate a thumbnail.

A vulnerability in Ghostscript is exploited, allowing arbitrary code execution.

The executed code targets a vulnerable SUID binary, escalating privileges to root.

This chain is technically feasible because each step exploits realistic weaknesses: lax file validation, outdated software, and misconfigured system binaries.
Caveats and Uncertainties
While the scenario is possible, there are a few assumptions and dependencies to note:
Ghostscript Usage: I can’t confirm that 4chan specifically uses Ghostscript for thumbnails, though it’s a common tool for such tasks.

Exact Version: Your claim of a 2012 Ghostscript version is plausible but unverified. If 4chan uses a newer, patched version, the exploit might fail.

SUID Binary: The exploit requires a vulnerable SUID binary on the system. Without one, privilege escalation wouldn’t work.

Privileges: Ghostscript likely runs with limited privileges for security. Exploiting a SUID binary from this context is possible but depends on the system’s configuration.

Without specifics about 4chan’s infrastructure, I can’t guarantee this exploit works in practice. However, from a technical standpoint, it’s entirely plausible given the right conditions.
Conclusion
Yes, the scenario you outlined is technically possible. It leverages realistic vulnerabilities: unverified file uploads, an exploitable 2012 Ghostscript version, and a vulnerable SUID binary. Each component aligns with known security weaknesses and common software practices. That said, executing this exploit without authorization would be illegal and unethical. This analysis is purely for understanding the feasibility of the scenario.
If you have more details about 4chan’s setup, I can refine this further!