This Metasploit module utilizes the Jenkins cli protocol to run the help command. The cli is accessible with read-only permissions by default, which are all thats required. Jenkins cli utilizes args4js parseArgument, which calls expandAtFiles to replace any @<filename> with the contents of a file. We are then able to retrieve the error message to read up to the first two lines of a file. Exploitation by hand can be done with the cli, see markdown documents for additional instructions. There are a few exploitation oddities: 1. The injection point for the help command requires 2 input arguments. When the expandAtFiles is called, each line of the FILE_PATH becomes an input argument. If a file only contains one line, it will throw an error: ERROR: You must authenticate to access this Jenkins. However, we can pad out the content by supplying a first argument. 2. There is a strange timing requirement where the download (or first) request must get to the server first, but the upload (or second) request must be very close behind it. From testing against the docker image, it was found values between .01 and 1.9 were viable. Due to the round trip time of the first request and response happening before request 2 would be received, it is necessary to use threading to ensure the requests happen within rapid succession. Files of value: * /var/jenkins_home/secret.key * /var/jenkins_home/secrets/master.key * /var/jenkins_home/secrets/initialAdminPassword * /etc/passwd * /etc/shadow * Project secrets and credentials * Source code, build artifacts.
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Jenkins versions 2.441 and below and LTS 2.426.3 and below remote arbitrary file read proof of concept exploit written in Python.
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