hacktricks/network-services-pentesting/49-pentesting-tacacs+.md

# 49 - Pentesting TACACS+

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## Basic Information

**Terminal Access Controller Access Control System (TACACS)** is a security protocol that provides centralized validation of users who are attempting to gain **access to a router or NAS**. TACACS+, a more recent version of the original TACACS protocol, provides separate authentication, authorization, and accounting (AAA) services.

```
PORT   STATE  SERVICE
49/tcp open   tacacs
```

**Default port:** 49

## Intercept Authentication Key

If an attacker manages to get in the middle between the client and the TACACS server, **he can intercept the authentication key** in encrypted form and then do a local bruteforce against it. So you both bruteforce the key and you don’t show up in the logs. And if you manage to bruteforce the key, **you’ll be able to access the network equipment and decrypt the traffic** in **Wireshark**.

### MitM

In order to perform a MitM attack you could use an [**ARP spoofing attack**](../generic-methodologies-and-resources/pentesting-network/#arp-spoofing).

### Brute-force Key

Now you need to run [Loki](https://c0decafe.de/svn/codename\_loki/trunk/). This is a special tool designed to analyze the security of L2/L3 protocols. Its capabilities are just as good as those of the popular **Yersinia** and it is a serious competitor to it. Loki can also bruteforce TACACS keys. If the key is successfully **bruteforced** (**usually in MD5 encrypted format)**, **we can access the equipment and decrypt the TACACS-encrypted traffic.**

```
sudo loki_gtk.py
```

<figure><img src="../.gitbook/assets/image (31) (2).png" alt=""><figcaption></figcaption></figure>

You also need to specify the path to the dictionary in order to bruteforce the encrypted key. Be sure to uncheck the **Use Bruteforce** option, otherwise Loki will bruteforce the password without using the dictionary.

<figure><img src="../.gitbook/assets/image (11) (2).png" alt=""><figcaption></figcaption></figure>

Now we have to wait for an administrator to log into the device through the TACACS server. It is assumed that the network administrator has already logged in, and we, **standing in the middle via ARP spoofing**, intercept the traffic. And in doing so, the legitimate hosts don’t realize that someone else has interfered with their connection.

<figure><img src="../.gitbook/assets/image (8) (2).png" alt=""><figcaption></figcaption></figure>

Now click the **CRACK** button and wait for **Loki** to break the password.

<figure><img src="../.gitbook/assets/image (17) (2).png" alt=""><figcaption></figcaption></figure>

### Decrypt Traffic

Great, we managed to unlock the key, now we need to decrypt the TACACS traffic. As I said, Wireshark can handle encrypted TACACS traffic if the key is present.

<figure><img src="../.gitbook/assets/image (28) (1).png" alt=""><figcaption></figcaption></figure>

We see which banner was used.

<figure><img src="../.gitbook/assets/image (24) (1) (2).png" alt=""><figcaption></figcaption></figure>

We find the username of the user `admin`

<figure><img src="../.gitbook/assets/image (7) (1) (1).png" alt=""><figcaption></figcaption></figure>

As a result, **we have the `admin:secret1234` credentials,** which can be used to access the hardware itself. **I think I’ll check their validity.**

<figure><img src="../.gitbook/assets/image (19) (2).png" alt=""><figcaption></figcaption></figure>

This is how you can attack TACACS+ and **gain access** to the control panel of network equipment.

## References

* The interception key section was copied from [https://medium.com/@in9uz/cisco-nightmare-pentesting-cisco-networks-like-a-devil-f4032eb437b9](https://medium.com/@in9uz/cisco-nightmare-pentesting-cisco-networks-like-a-devil-f4032eb437b9)

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