To decode theCommand and Control (C2) hostfrom thepcap_artifact5.txtfile, follow these detailed steps:

Step 1: Access the File

Log into the Analyst Desktop.

Navigate to theDesktopand locate the file:

pcap_artifact5.txt

Open the file using a text editor:

OnWindows:

nginx

notepad pcap_artifact5.txt

OnLinux:

cat ~/Desktop/pcap_artifact5.txt

Step 2: Examine the File Contents

Check the contents to identify the encoding format. Typical encodings used for C2 communication include:

Base64

Hexadecimal

URL Encoding

ROT13

Example File Content (Base64 format):

nginx

aHR0cDovLzEwLjEwLjQ0LjIwMDo4MDgwL2NvbW1hbmQucGhw

Step 3: Decode the Contents

Method 1: Using PowerShell (Windows)

OpenPowerShelland decode:

powershell

$encoded = Get-Content "C:\Users\\Desktop\pcap_artifact5.txt"

[System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($encoded))

This will print the decoded content directly.

Method 2: Using Linux

Usebase64 decoding:

base64 -d ~/Desktop/pcap_artifact5.txt

If the content ishexadecimal, convert it as follows:

xxd -r -p ~/Desktop/pcap_artifact5.txt

If it appearsURL encoded, use:

echo -e $(cat ~/Desktop/pcap_artifact5.txt | sed 's/%/\\x/g')

Step 4: Analyze the Decoded Output

If the output appears like a URL or an IP address, that is likely theC2 host.

Example Decoded Output:

arduino

http://10.10.44.200:8080/command.php

TheC2 hostis:

10.10.44.200

Step 5: Cross-Verify the C2 Host

OpenWiresharkand load the relevant PCAP file to cross-check the IP:

mathematica

File > Open > Desktop > Investigations > ransom.pcap

Filter for C2 traffic:

ini

ip.addr == 10.10.44.200

Validate the C2 host IP address through network traffic patterns.

Answer:

10.10.44.200

Step 6: Document the Finding

Record the following details:

Decoded C2 Host:10.10.44.200

Source File:pcap_artifact5.txt

Decoding Method:Base64 (or the identified method)

Step 7: Next Steps

Threat Mitigation:

Block the IP address10.10.44.200at the firewall.

Conduct anetwork-wide searchto identify any communications with the C2 server.

Further Analysis:

Check other PCAP files for similar traffic patterns.

Perform adeep packet inspection (DPI)to identify malicious data exfiltration.