In our previous blog, we saw technical details and fix recommendations from various security agencies and security professionals.
According to multiple reports, this Petya ransomware campaign has infected organizations in several sectors including finance, transportation, energy, commercial facilities, and healthcare. While these victims are business entities, other Windows systems without patches installed for the vulnerabilities in MS17‑010, CVE-2017-0144, and CVE-2017-0145 are at risk of infection.
Negative consequences of ransomware infection include the following:
- temporary or permanent loss of sensitive or proprietary information,
- disruption to regular operations,
- financial losses incurred to restore systems and files, and
- potential harm to an organization’s reputation.
NCCIC recommends against paying ransoms; doing so enriches malicious actors while offering no guarantee that the encrypted files will be released. In this incident, the email address for payment validation was shut down by the email provider, so payment is especially unlikely to lead to data recovery. (link is external) According to the reports, below sites are C2 payment sites for this activity. These sites are not included in the CSV package as IOCs.
Organizations are recommended to coordinate with their security vendors to ensure appropriate coverage for this threat. Because there is overlap between the WannaCry and Petya activities, many of the available rulesets can protect against both malware strains when appropriately implemented. The following rulesets provided in publically available sources may help detect this activity:
- sid:2001569, “ET SCAN Behavioral Unusual Port 445 traffic Potential Scan or Infection”(link is external)
- sid:2012063, “ET NETBIOS Microsoft SRV2.SYS SMB Negotiate ProcessID? Function Table Dereference (CVE-2009-3103)”(link is external)
- sid:2024297, “ET CURRENT_EVENTS ETERNALBLUE Exploit M2 MS17-010”(link is external)
Recommended Steps for Prevention
- Apply the Microsoft patch for the MS17-010 SMB vulnerability dated March 14, 2017.(link is external)
- Enable strong spam filters to prevent phishing emails from reaching the end users and authenticate in-bound email using technologies like Sender Policy Framework (SPF), Domain Message Authentication Reporting and Conformance (DMARC), and DomainKeys Identified Mail (DKIM) to prevent email spoofing.
- Scan all incoming and outgoing emails to detect threats and filter executable files from reaching the end users.
- Ensure anti-virus and anti-malware solutions are set to automatically conduct regular scans.
- Manage the use of privileged accounts. Implement the principle of least privilege. No users should be assigned administrative access unless absolutely needed. Those with a need for administrator accounts should only use them when necessary.
- Configure access controls including file, directory, and network share permissions with least privilege in mind. If a user only needs to read specific files, they should not have write access to those files, directories, or shares.
- Disable macro scripts from Microsoft Office files transmitted via email. Consider using Office Viewer software to open Microsoft Office files transmitted via email instead of full Office suite applications.
- Develop, institute, and practice employee education programs for identifying scams, malicious links, and attempted social engineering.
- Run regular penetration tests against the network, no less than once a year. Ideally, run these as often as possible and practical.
- Test your backups to ensure they work correctly upon use.
- Utilize host-based firewalls and block workstation-to-workstation communications.
Recommendations for Network Protection
- Disable SMBv1 and
- Block all versions of SMB at the network boundary by blocking TCP port 445 with related protocols on UDP ports 137-138 and TCP port 139, for all boundary devices.
Note: disabling or blocking SMB may create problems by obstructing access to shared files, data, or devices. The benefits of mitigation should be weighed against potential disruptions to users.
Review US-CERT’s Alert on The Increasing Threat to Network Infrastructure Devices and Recommended Mitigations  and consider implementing the following best practices:
- Segregate networks and functions.
- Limit unnecessary lateral communications.
- Harden network devices.
- Secure access to infrastructure devices.
- Perform out-of-band network management.
- Validate integrity of hardware and software.
Recommended Steps for Remediation
- Contact law enforcement. We strongly encourage you to contact a local Cyber Security Incidence Report office upon discovery to report an intrusion and request assistance. Maintain and provide relevant logs.
- Implement your security incident response and business continuity plan. Ideally, organizations should ensure they have appropriate backups so their response is simply to restore the data from a known clean backup.
General Advice for Defending Against Ransomware
Precautionary measures to mitigate ransomware threats include:
- Ensure anti-virus software is up-to-date.
- Implement a data backup and recovery plan to maintain copies of sensitive or proprietary data in a separate and secure location. Backup copies of sensitive data should not be readily accessible from local networks.
- Scrutinize links contained in emails, and do not open attachments included in unsolicited emails.
- Only download software—especially free software—from sites you know and trust.
- Enable automated patches for your operating system and Web browser.
Until next time, stay secure.
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-  Bleeping Computer: Email Provider Shuts Down Petya Inbox Preventing Victims From Recovering Files(link is external)
-  Emerging Threats 2001569(link is external)
-  Emerging Threats 2012063(link is external)
-  Emerging Threats 2024297(link is external)
-  Microsoft: Security Bulletin MS17-010(link is external)
-  US-CERT: The Increasing Threat to Network Infrastructure Devices and Recommended Mitigations
-  F-Secure: (Eternal) Petya from a Developer’s Perspective(link is external)
-  Microsoft |TechNet: New ransomware, old techniques: Petya adds worm capabilities(link is external)
-  US-CERT: Ransomware and Recent Variants
- US-CERT: Petya Ransomware