Forensic Investigation Process Following a Ransomware Attack
The forensics investigation after a ransomware attack is a critical component of the response effort, involving specialized techniques and methodologies.
As soon as a ransomware attack is detected, the initial response should focus on containing the threat to prevent further spread and preserving evidence for forensic analysis. This step is critical and should be initiated immediately.
NOTE: In an ideal scenario, the forensic investigation and recovery processes following a ransomware attack should be conducted concurrently, rather than sequentially (see **CONCURRENT ACTIVITIES** below).
Identification and Preservation of Evidence
The first step is to identify all sources of potential evidence, including infected machines, servers, logs, network traffic data, and backups.
Forensic experts work to preserve the state of these systems as they were at the time of the attack, to avoid tampering or loss of evidence. This often involves creating digital copies (forensic images) of affected systems.
Experts analyze the ransomware code to understand its functionality, including encryption methods, communication with command-and-control servers, and any unique characteristics that might help identify the attackers or find a decryption key.
This analysis helps in determining the ransomware family and potentially linking it to known criminal groups.
REvil (Sodinokibi) - Known for high-profile attacks and the "double extortion" tactic.
DarkSide - Gained attention for the Colonial Pipeline attack; operates on a "Ransomware-as-a-Service" model.
Conti - A sophisticated group targeting large corporations and government agencies, using double extortion methods.
Maze - One of the first to use double extortion, threatening to release stolen data if ransoms aren't paid.
Ryuk - Targets large organizations, especially in healthcare and public sectors, with well-planned attacks.
LockBit - Known for aggressive tactics and rapid encryption speed, operating as a ransomware-as-a-service.
DoppelPaymer - Emerged from BitPaymer, known for attacks against public sector, healthcare, and critical industries.
NetWalker - Targets healthcare and educational institutions, particularly active during the COVID-19 pandemic.
Forensic investigators trace back the attackers' steps to identify how they gained access. Common vectors include phishing emails, unpatched software vulnerabilities, or compromised credentials.
Understanding the attack vector is crucial for closing security gaps and preventing future attacks.
Investigators reconstruct the timeline of the attack, determining when the ransomware was deployed, when it began encrypting files, and any relevant actions taken by the attackers.
Log Analysis and Network Traffic Review
Analysis of logs from servers, firewalls, intrusion detection systems, and other sources is conducted to trace the attackers' actions within the network.
Network traffic is reviewed to identify any communication with known malicious IP addresses or domains.
Part of the forensic process involves attempting to recover lost or encrypted data. This can be challenging with ransomware, but sometimes forensic tools can recover deleted files or remnants of unencrypted data.
The key challenge is to balance the urgency of restoring operations with the thoroughness needed in the forensic investigation. Cutting corners in either process can lead to inadequate recovery or insufficient understanding of the attack, potentially resulting in further vulnerabilities.
Investigators may attempt to attribute the attack to specific threat actors, though this can be difficult. Attribution can be important for legal and strategic responses.
A comprehensive report is prepared detailing the findings, including the attack vector, the impact, recommendations for future security improvements, and compliance-related information.
If the attack is significant, or if sensitive data was compromised, the incident may be reported to law enforcement agencies. Forensic investigators might collaborate with them, providing evidence for potential legal action against the attackers.
After the investigation, a review is conducted to identify lessons learned and to recommend improvements in security practices, policies, and response plans.
Both the forensic and the recovery teams should document their actions and findings. This documentation is critical for insurance claims, legal compliance, and improving the organization's future cybersecurity posture.
In a typical scenario, a preliminary assessment might be completed within days to a week, providing initial insights and guiding immediate response efforts. However, a comprehensive investigation that includes full analysis, reporting, and recommendations for future prevention can extend much longer. It's important for organizations to balance the need for a thorough investigation with the urgency of resuming normal operations, always keeping in mind the potential long-term implications of the attack.
Forensic Investigation: While containment measures are being implemented, a forensic team can start their investigation. This team works on understanding the attack vector, the extent of the breach, and gathering evidence. It's important that this process does not interfere with or delay the recovery efforts.
Recovery Efforts: Simultaneously, another team should work on the recovery process. This includes eradicating the ransomware, restoring data from backups, and ensuring that restored systems are not vulnerable to the same attack.
The key challenge is to balance the urgency of restoring operations with the thoroughness needed in the forensic investigation. Cutting corners in either process can lead to inadequate recovery or insufficient understanding of the attack could expose you to additional risk.
Throughout the forensic investigation, maintaining the integrity of the evidence and following a methodology that is acceptable in a court of law is essential, especially if legal actions against the perpetrators are considered. The findings from a forensic investigation not only aid in recovering from the current attack but are also instrumental in bolstering defenses against future threats