See the solution in Explanation.
Explanation:
To identify thefull User-Agent valueassociated with theransomware demand file downloadfrom the ransom.pcapfile, follow these detailed steps:
Step 1: Access the PCAP File
* Log into the Analyst Desktop.
* Navigate to theInvestigationsfolder located on the desktop.
* Locate the file:
ransom.pcap
Step 2: Open the PCAP File in Wireshark
* LaunchWireshark.
* Open the PCAP file:
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File > Open > Desktop > Investigations > ransom.pcap
* ClickOpento load the file.
Step 3: Filter HTTP Traffic
Since ransomware demands are often served astext files (e.g., README.txt)via HTTP/S, use the following filter:
http.request or http.response
* This filter will show bothHTTP GETandPOSTrequests.
Step 4: Locate the Ransomware Demand File Download
* Look for HTTPGETrequests that include common ransomware filenames such as:
* README.txt
* DECRYPT_INSTRUCTIONS.html
* HELP_DECRYPT.txt
* Right-click on the suspicious HTTP packet and select:
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Follow > HTTP Stream
* Analyze theHTTP headersto find theUser-Agent.
Example HTTP Request:
GET /uploads/README.txt HTTP/1.1
Host: 10.10.44.200
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.5414.75 Safari/537.36 Step 5: Verify the User-Agent
* Check multiple streams to ensure consistency.
* Confirm that theUser-Agentbelongs to the same host(10.10.44.200)involved in the ransomware incident.
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Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.
0.5414.75 Safari/537.36
Step 6: Document and Report
* Record the User-Agent for analysis:
* PCAP Filename:ransom.pcap
* User-Agent:Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.5414.75 Safari/537.36
* Related File:README.txt
Step 7: Next Steps
* Forensic Analysis:
* Look for more HTTP requests from the sameUser-Agent.
* Monitor Network Activity:
* Identify other systems with the same User-Agent pattern.
* Block Malicious Traffic:
* Update firewall rules to block any outbound connections to suspicious domains.