PayPal Remote Code Execution Vulnerability Patched


So this is a big one, and thankfully this PayPal Remote Code Execution Vulnerability was discovered by security researchers and not the bad guys. Although there’s no way for us to know if someone has been using this to siphon data out of PayPal for some time before the whitehats found it.

PayPal Remote Code Execution Vulnerability Patched

It’s a roundabout bug that turns out serious, and why I tell developers don’t mess with serialised data – it’s ugly. In this case object deserialisation in Java basically allowed for remote command execution on PayPal servers.

Independent security researcher Michael Stepankin has reported a since-patched remote code execution hole in Paypal that could have allowed attackers to hijack production systems.

The critical vulnerability affecting manager.paypal.com revealed overnight was reported 13 December and patched soon after disclosure.

It allowed Stepankin to execute arbitrary shell commands on PayPal web servers through Java object deserialisation opening access to production databases.

“I immediately reported this bug to PayPal security team and it was quickly fixed after that,” Stepankin says

“While security testing of manager.paypal.com, my attention was attracted by unusual post form parameter “oldFormData” that looks like a complex object after base64 decoding.


It was reported responsibly and fixed fairly quickly, PayPal does have quite a good record of reacting in a timely fashion.

You can read the original blog post here: PayPal Remote Code Execution Vulnerability

“After some research I realised that it’s a Java serialised object without any signature handled by the application [which] means that you can send serialised object of any existing class to a server and ‘readObject’ or ‘readResolve’ method of that class will be called.”

Attackers would need to follow the technique disclosed by FoxGlove Security to gain remote code execution.

Stepankin says he used their ‘ysoserial’ payload generation tool in his attack.

PayPal handed out US$5000 for the bug even though it was a duplicate of a report sent in two days prior by researcher Mark Litchfield. Most bug bounty operators do not pay for duplicates making the payment unusual.

Strangely enough it seems to like two researchers found the same bug within days of each other independently. So PayPal paid them both a bounty, which is very rare – and pretty cool IMHO.

You can read about what Mark Litchfield got upto in December here – My $50k Personal Challenge – Results

Pretty good earnings for a months work, although I might imagine he’s had a fair number of those bugs in pocket for a while.

Source: The Register

Posted in: Exploits/Vulnerabilities, Web Hacking

, ,


Latest Posts:


Sooty - SOC Analyst All-In-One CLI Tool Sooty – SOC Analyst All-In-One CLI Tool
Sooty is a tool developed with the task of aiding a SOC analyst to automate parts of their workflow and speed up their process.
UBoat - Proof Of Concept PoC HTTP Botnet Project UBoat – Proof Of Concept PoC HTTP Botnet Project
UBoat is a PoC HTTP Botnet designed to replicate a full weaponised commercial botnet like the famous large scale infectors Festi, Grum, Zeus and SpyEye.
LambdaGuard - AWS Lambda Serverless Security Scanner LambdaGuard – AWS Lambda Serverless Security Scanner
LambdaGuard is a tool which allows you to visualise and audit the security of your serverless assets, an open-source AWS Lambda Serverless Security Scanner.
exe2powershell - Convert EXE to BAT Files exe2powershell – Convert EXE to BAT Files
exe2powershell is used to convert EXE to BAT files, the previously well known tool for this was exe2bat, this is a version for modern Windows.
HiddenWall - Create Hidden Kernel Modules HiddenWall – Create Hidden Kernel Modules
HiddenWall is a Linux kernel module generator used to create hidden kernel modules to protect your server from attackers.
Anteater - CI/CD Security Gate Check Framework Anteater – CI/CD Security Gate Check Framework
Anteater is a CI/CD Security Gate Check Framework to prevent the unwanted merging of filenames, binaries, deprecated functions, staging variables and more.


Comments are closed.