SNMP penetration testing is a process for scanning networks and testing for vulnerabilities in Simple Network Management Protocols. Through this process, security teams can conduct comprehensive security assessments and analyses on SNMP-enabled devices, ensuring secure networks and compliance with relevant regulations.

SNMP review

SNMP (Simple Network Management Protocol) is a protocol used for network management and monitoring. It allows network administrators to monitor network devices, including servers, routers, switches, printers, and other devices, and collect information such as device uptime, CPU usage, memory usage, and network traffic statistics.

SNMP uses a hierarchical structure called the Management Information Base (MIB) to organize and manage the data that is collected from network devices.

SNMP is composed of three main components:

• SNMP manager

• SNMP agent

• MIBs

The SNMP manager is a network management system that monitors and controls SNMP-enabled devices.

The SNMP agent is software that runs on the SNMP-enabled device and provides information to the SNMP manager.

MIBs are typically structured as a tree-like hierarchy, with each node in the tree representing a different aspect of the device being monitored. The top level of the MIB hierarchy is known as the root node, and subsequent levels of the hierarchy are defined by different organizations.

SNMP is typically configured with one or more community strings, which are used to authenticate and authorize SNMP requests.

There are two types of community strings:

• read-only (RO)

• read-write (RW)

RO community strings allow SNMP requests to retrieve information from the SNMP-enabled device, while RW community strings allow SNMP requests to modify information on the SNMP-enabled device.

SNMP has several versions, including SNMPv1, SNMPv2, and SNMPv3. SNMPv1 and SNMPv2 do not provide any authentication or encryption mechanisms, making them susceptible to eavesdropping, tampering, and replay attacks.

SNMPv3 provides authentication and encryption mechanisms, but can still be vulnerable to misconfigurations that allow attackers to bypass these security measures.

SNMP Reconnaissance

Identify the SNMP services running on the target system(s) using tools like Nmap. Determine the SNMP version being used (v1, v2c, or v3), as well as the community strings and other SNMP configurations.

Use Nmap to identify SNMP services running on a target system using the following command:

nmap -sU -p 161 --script snmp-*

SNMP (Simple Network Management Protocol) uses two ports for communication:

• UDP port 161

• UDP port 162

UDP port 161 is used by SNMP managers to send requests to SNMP agents on network devices. SNMP agents listen on port 161 for incoming SNMP requests. When a request is received, the agent processes the request and sends a response back to the manager on the same port.

UDP port 162 is used by SNMP agents to send SNMP traps to SNMP managers. SNMP traps are notifications that are sent by the agent to the manager to indicate an event or error condition, such as a device going down or reaching a certain threshold for a particular metric.

SNMP Enumeration

SNMP enumeration is the process of remotely querying a device to extract its management data, such as names of users, shares, and services. With this information, an attacker can further exploit a network by having access to confidential data and elevated privileges.

Use SNMP enumeration tools like snmpenum or snmpwalk to gather information such as system details, user accounts, network topology, and SNMP object identifiers (OIDs).

snmp-check

SNMP Exploitation

Attempt to exploit any discovered vulnerabilities. For example, SNMPv1 and SNMPv2c use community strings for authentication, which can be easily brute-forced. SNMPv3, on the other hand, uses more secure authentication methods, but may still be vulnerable to certain attacks.

SNMPwn is a tool for testing SNMP configurations and identifying vulnerabilities, including weak community strings, SNMPv3 user enumeration, and default passwords.

snmpwn -t -u -p

Yersinia is a network security tool that includes modules for testing SNMP vulnerabilities, including community string guessing and brute-forcing.

yersinia snmp -I eth0 -C public -T

Metasploit is another popular penetration testing framework that includes modules for exploiting SNMP vulnerabilities.

use auxiliary/scanner/snmp/snmp_login

set RHOSTS

set COMMUNITY

public run

Privilege escalation

If you have access to a limited user account on the system, try to escalate your privileges using SNMP. This can be done by querying privileged OIDs or by leveraging SNMP vulnerabilities to execute arbitrary code.

Post-exploitation

Once you have gained access to the system, perform post-exploitation tasks like gathering sensitive data, creating backdoors, or installing malware.

Clean-up

Ensure that any changes made during the pentesting process are reversed and that the system is left in its original state.