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Investigating Ransomware

Investigating ransomware requires a structured approach that identifies how the attackers entered the system, how the ransomware executed, what files were encrypted, whether data was exfiltrated, and what persistence or lateral movement took place. Ransomware investigations focus heavily on system logs, disk artifacts, memory captures, and network traffic to reconstruct the attack chain.

Understanding Ransomware Behavior

Ransomware typically follows a predictable pattern:

  • Initial access (phishing, RDP compromise, exploit)

  • Privilege escalation

  • Credential harvesting

  • Lateral movement

  • Payload deployment

  • File encryption

  • Data exfiltration (double/triple extortion)

  • Cleanup and ransom note creation

Investigators must trace each stage to determine impact.

Evidence Sources for Ransomware Investigations

1. Windows Event Logs

Look for:

  • Logon events

  • Service creation

  • Scheduled tasks

  • PowerShell activity

  • Remote access attempts

Security, System, and PowerShell logs are critical.

2. Sysmon Logs

Reveal:

  • Process creation

  • Parent-child relationships

  • Suspicious command lines

  • Network connections

  • File modifications

Sysmon dramatically improves ransomware visibility.

3. Disk Artifacts

From:

  • MFT

  • Prefetch files

  • LNK shortcuts

  • Jump lists

  • Registry keys

  • Amcache

  • SRUM

These artifacts show execution traces and user behavior.

4. Memory Evidence

Memory captures reveal:

  • Active encryption processes

  • Keys stored in RAM (rare, but possible)

  • Injected code

  • Malware threads

  • Network connections

Tools like Volatility and Rekall help extract details.

5. Network Traffic

Indicators include:

  • C2 connections

  • Exfiltration behavior

  • Beaconing patterns

  • Suspicious IPs/domains

  • SMB lateral movement

PCAPs and firewall logs are essential.

6. Cloud Logs

If cloud resources were targeted:

  • IAM manipulation

  • Storage access

  • VM modifications

  • API calls

Used to track ransomware in cloud environments.

Steps to Investigate a Ransomware Incident

1. Identify the Initial Access Vector

Common methods:

  • Phishing emails

  • Exploited vulnerabilities

  • Compromised RDP

  • VPN credential theft

  • Supply chain infections

Evidence to check:

  • Email logs

  • Authentication logs

  • VPN logs

  • Web server logs

  • Patch state

2. Examine Execution Artifacts

Ransomware leaves traces of execution.

Investigate:

  • Prefetch files

  • Amcache entries

  • Program Execution registry keys

  • MFT timestamps

  • LNK files

  • File creation patterns

These show when and how the ransomware ran.

3. Map the Encryption Process

Ransomware actions often include:

  • File modification bursts

  • Creation of ransom notes

  • Deletion of shadow copies

  • Renamed or locked files

Evidence to check:

  • VSS deletions

  • Modified file extensions

  • File entropy spikes

  • Log entries showing mass file access

4. Investigate Lateral Movement

Attackers may spread ransomware across hosts.

Tools used:

  • PsExec

  • RDP

  • SMB

  • WMI

  • PowerShell Remoting

Artifacts to correlate:

  • Sysmon Event ID 1 (process)

  • Event ID 4624/4625 (logon)

  • Event ID 7045 (service creation)

  • Network connections

5. Check for Data Exfiltration

Modern ransomware groups steal data before encryption.

Indicators:

  • Large outbound transfers

  • Unusual DNS queries

  • Cloud storage uploads

  • FTP/SFTP outbound traffic

  • Compressed archives created locally

Check:

  • Firewall logs

  • Proxy logs

  • Sysmon network events

  • Cloud access logs

6. Identify Persistence Mechanisms

Attackers may establish persistence for later return.

Common techniques:

  • Run keys

  • Scheduled tasks

  • Services

  • Registry modifications

  • Startup folder additions

  • Backdoor accounts

Registry and syslog analysis helps locate persistence.

7. Verify Ransomware Variant

Identification helps determine:

  • Encryption algorithm

  • Known recoverability

  • IOCs

  • MITRE techniques

  • Ransom group behavior

Use:

  • Malware analysis

  • YARA rules

  • Known ransomware signatures

  • Threat intelligence feeds

8. Determine the Scope of Impact

Assess:

  • Number of encrypted files

  • Affected hosts

  • Lateral spread

  • Domain compromise

  • Exfiltrated data

  • Persistence across systems

Mapping scope is critical for containment and recovery.

Key Artifacts to Examine in Ransomware Cases

1. Prefetch files

Indicate execution and related file paths.

2. Amcache

Records program execution and metadata.

3. $MFT

Shows file creation and modification timestamps.

4. VSS deletion logs

Common command:

vssadmin.exe delete shadows /all

5. Sysmon

Logs malicious processes or PowerShell commands.

6. Event logs

Highlight privilege escalation or remote access.

7. Browser history

May show command-and-control panels or downloads.

8. USB activity

Potential data theft vector.

Signs of Ransomware Activity

  • Sudden file renaming

  • Increased CPU usage

  • New suspicious processes

  • Network scanning or brute-force attempts

  • VSS deletion commands

  • Ransom note files appearing globally

  • High-volume SMB traffic

  • Failed backup access

  • Suspicious PowerShell executions

Common Ransomware Tools and Behaviors

Cobalt Strike / Meterpreter

Used for initial access and lateral movement.

Built-in Windows Tools

Attackers often use:

  • net.exe

  • wmic.exe

  • powershell.exe

  • vssadmin.exe

  • schtasks.exe

Compression Tools

Used for staging exfiltration:

  • WinRAR

  • 7zip

  • PowerShell Compress-Archive

Tools Used in Ransomware Investigations

  • KAPE

  • Volatility

  • ELK Stack

  • Timesketch

  • Autopsy / Sleuth Kit

  • Velociraptor

  • Plaso

  • Sysmon

  • EDR tools

  • YARA scanners

  • Network analyzers (Zeek, Wireshark)

Intel Dump

  • Ransomware investigations focus on initial access, lateral movement, execution artifacts, encryption behavior, persistence, and exfiltration.

  • Key evidence sources include Windows logs, Sysmon, disk artifacts (MFT, registry, LNK), memory captures, PCAPs, and cloud logs.

  • Investigators reconstruct the attack chain, identify ransomware variants, confirm data theft, detect persistence, and measure scope of impact.

  • Tools like Volatility, KAPE, Timesketch, ELK, Plaso, and EDR telemetry are central to timeline and behavior analysis.

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