Tryhackme - Summit room write-up - Easy

Tryhackme - Summit room write-up - Easy


This goal of this TryHackMe this room is to review the different ways to perform malware detection based on the Pyramid of Pain (which can be learnt on THM : and on the MITRE ATT&CK framework.

The link of this room :

If we open the website of the room, we’ll see a mailbox with 4 mails. One of these is sent from the Sphinx which will send us malwares to analyse. We will have to make sure these malwares are detected by the system by making new detection rules.

The first Sphinx email : site1

Pyramid’s level 1 : Hash values

We can use the left panel of the website to access the malware sandbox tool.

The analysis of the first malware (sample1.exe) : analyse1

The only information we have at this point to identify this malware is its hash. We can make a detection rule in the Manage Hashes tool : hash1

The Sphinx then send us a second mail with the first flag and a new malware to analyse. It will be the same for all malwares.

Pyramid’s level 2 : IP Adresses

The analysis of the second malware reveals it’s making a connection to a certain IP address : analyse2

We can make a rule to deny this connection in the Firewall Manager tool : rule1

The goal here is for example stopping data to be exfiltrated, so we Deny connection from (Egress) Any to the address we found.

Pyramid’s level 3 : Domain Names

The analysis of the third malware reveals that it’s making a connection to a certain domain name (especially on an unsual port) : analyse3

We then make a rule to Deny a connection to this domain name in the DNS Filter tool. We categorize the connection in the type Malware. rule2

Pyramid’s level 4 : Network/Host artifacts

The analysis of the fourth malware reveals that it’s modifying windows registry : analyse4

Here we can see that the malware is modifying the registry in order to disable the real time protection of the windows defender anti-virus (first modification).

We will make a sigma rule in the Sigma Rule Builder tool to detect this modification in the future. We choose Sysmon Event Logs, then Registry Modification, then we enter this input : rule3

In clear, this means that if some program try to write 1 in this registry, it will be detected as a threat.

Pyramid’s level 5 : Tools

Our friend the Spinx is sending it’s server backend logs instead of a malware this time : log1

In this log, the first thing we can see is that 97 bytes are sent from the unique source to every 30 minutes. This is a sign of a tool exfiltrating data or communicating with a C2 (command & control) server.

We won’t deny connection to the IP found in the log because it could change in the future. We can instead make a sigma rule to detect the activity we mentioned. In the section Sysmon Event Logs/Network Connections, we can input : rule4

As we know, the attacker IP and port can change. We will detect the network activity based on the behaviour of the attacker’s tool :

We categorize this activity as Command and Control as it’s communicating with the Sphinx’s remote backend server.

Pyramid’s level 6 : TTP

TTP stands for Tactics, Techniques and Procedures. This level of the pyramid consists in deeply analyse what the malware is doing on the system and what technique/tool he is using.

This time, the Sphinx sent us the log containing the commands his malware is executing on the system : log2

We can see that it’s using a file name exfiltr8.log in the %temp% directory in order to exfiltrate data.

We can build a sigma rule to detect the modification of this file as malicious : rule5

The Sphinx will then send his last mail to us with the last flag : final_mail