The tactics described in “Operation Poisoned Hurricane” should come as a stark reminder that advanced threat actors do not stand still. They continue to refine their tradecraft, finding new and innovative ways to bypass security controls and evade detection.
The technical details of the evasion techniques are complex, but the lessons for the CISO are clear:
- Traffic to a legitimate website is not always legitimate traffic – malware could be hiding command and control communications in traffic to reputable sites.
- Don’t allow direct Internet access, ever. The DNS hijacking described in the blog relies on directly sending DNS queries.
- File-based malware controls are being successfully evaded in the wild.
What can you do to protect your organisation from these threats? My suggestions are:
- Make sure you have a well-architected Internet proxy architecture that prevents direct connectivity from your network:
- Never allow hosts other than your secure external DNS resolver to send DNS queries to the Internet. Period.
- Record all internal DNS queries, these are a possible sign of a compromised machine.
- Put in place a malware detection solution that can identify multi-vector, multi-stage malware execution:
- These attacks used legitimate, signed binaries from a known security company to load malicious code contained in other files as part of a multi-stage attack. File-oriented security controls do not detect these attacks, you need a full behavioural analytics engine to see the attack.
- Don’t assume that a signed binary is safe. Automated analysis of code behaviour in an execution environment is critical.
- Ensure you can detect and block command & control traffic from compromised users, even if it is to legitimate websites:
- Sophisticated attackers can use blogs, code repositories, even comments on social media, to send and receive command & control signals.
- Reputation-based detection is not sufficient, you need detection and protection that can understand new command and control tactics based on automated behavioural analysis.
The attackers are evolving their attacks, are you evolving your defenses fast enough to keep them out?