Cybersecurity agencies in Australia, Canada, New Zealand, the United Kingdom, and the United States have published a joint advisory focusing on detecting malicious activity and incident response.
Best practice incident response procedures, the report notes, start with the collection of artifacts, logs, and data, and their removal for further analysis, and continue with implementing mitigation steps without letting the adversary know that their presence in the compromised environment has been detected.
Furthermore, the joint advisory encourages organizations to collaborate with a third-party IT security organization to receive technical support, ensure that the adversary has been removed from the network, and avoid issues resulting from follow-up compromises.
The joint advisory “highlights technical approaches to uncovering malicious activity and includes mitigation steps according to best practices. The purpose of this report is to enhance incident response among partners and network administrators along with serving as a playbook for incident investigation.”
Technical approaches to uncovering malicious activity include searching for Indicators of Compromise (IOC), analysis of traffic patterns in both network and host systems, analysis of data to discover repeating patterns, and anomaly detection.
Organizations are advised to look for a broad variety of artifacts when conducting network investigations or host analysis, including DNS traffic, RDP, VPN, and SSH sessions, rogue processes, new applications, registry keys, open ports, established connections, user login data, PowerShell commands, and more.
When handling an incident, organizations should also avoid common errors, such as taking immediate action after identifying compromised systems (which may tip off the adversary), mitigating the systems before artefacts are secured and recovered, accessing/blocking the adversary infrastructure, preemptively resetting credentials, erasing log data, or failing to address the root cause of an attack.
Mitigation steps that organizations should take when looking to prevent common attack vectors include restricting or discontinuing FTP, Telnet, and non-approved VPN services; removing unused services and systems; quarantining compromised hosts; closing unnecessary ports and protocols; disabling remote network administration tools; resetting passwords; and patching vulnerabilities in a timely manner, among others.
The advisory also details recommendations and best practices for organizations to apply when looking to improve their security stance and prevent cyber-attacks from happening, but underlines the fact that no single technique, program, or set of defensive measures could fully prevent intrusions.
“Properly implemented defensive techniques and programs make it more difficult for a threat actor to gain access to a network and remain persistent yet undetected. When an effective defensive program is in place, attackers should encounter complex defensive barriers. Attacker activity should also trigger detection and prevention mechanisms that enable organizations to identify, contain, and respond to the intrusion quickly,” the advisory reads.
Network segmentation, physical segregation of sensitive data, adopting the principles of least privilege, and applying recommendations and implementing secure configurations across the network segments and layers should help diminish the harm in the event of an attack.