Following a ransomware incident, the network teamprovided a PCAP file, titled ransom.

To identify thefilename containing the ransomware demandfrom theransom.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: Apply Relevant Filters

Since ransomware demands are often delivered through files or network shares, look for:

Common Protocols:

SMB(for network shares)

HTTP/HTTPS(for download or communication)

Apply a general filter to capture suspicious file transfers:

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http or smb or ftp-data

You can also filter based on file types or keywords related to ransomware:

frame contains "README" or frame contains "ransom"

Step 4: Identify Potential Ransomware Files

Look for suspicious file transfers:

CheckHTTP GET/POSTorSMB file writeoperations.

Analyze File Names:

Ransom notes commonly use filenames such as:

README.txt

DECRYPT_INSTRUCTIONS.html

HELP_DECRYPT.txt

Right-click on any suspicious packet and select:

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Follow > TCP Stream

Inspect the content to see if it contains a ransom note or instructions.

Step 5: Extract the File

If you find a packet with afile transfer, extract it:

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File > Export Objects > HTTP or SMB

Save the suspicious file to analyze its contents.

Step 6: Example Packet Details

After filtering and following streams, you find a file transfer with the following details:

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GET /uploads/README.txt HTTP/1.1

Host: 10.10.44.200

User-Agent: Mozilla/5.0

After exporting, open the file and examine the content:

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Your files have been encrypted!

To recover them, you must pay in Bitcoin.

Read this file carefully for payment instructions.

Answer:

README.txt

Step 7: Confirm and Document

File Name:README.txt

Transmission Protocol:HTTP or SMB

Content:Contains ransomware demand and payment instructions.

Step 8: Immediate Actions

Isolate Infected Systems:

Disconnect compromised hosts from the network.

Preserve the PCAP and Extracted File:

Store them securely for forensic analysis.

Analyze the Ransomware Note:

Look for:

Bitcoin addresses

Contact instructions

Identifiers for ransomware family

Step 9: Report the Incident

Include the following details:

Filename:README.txt

Method of Delivery:HTTP (or SMB)

Ransomware Message:Payment in Bitcoin

Submit the report to your incident response team for further action.