This guest blog was provided by Dirk Schrader, Global VP of Security Research at NNT, now part of Netwrix
An ongoing malware campaign recently documented by Cisco’s Talos Group, abuses the public cloud infrastructures of the likes of Amazon’s AWS and Microsoft’s Azure cloud services. This ‘activity’ means that threat actors are moving towards a fully dynamic attack infrastructure with the intention to circumvent initial distribution and access detection in ways unseen so far. Cybersecurity professionals are calling for Microsoft and Amazon to step up protections from misused public cloud instances in their possession. This could only slow down the attackers as they will turn to hijacked infrastructure.
Attackers distributing malware using phishing emails with malicious attachments is nothing new. Once the attachment in the phishing email is opened, the second stage of a malware campaign is to ‘get in’.
While previous campaigns have been successfully thwarted at this stage, this one comes with a couple of new tricks. First of all, usage of a public cloud instances makes it difficult to dissect the malicious traffic from legitimate IP traffic to those cloud providers and solution providers using them. Moreover, this time the attackers also run a dynamic domain name scheme that is designed to render DNS based filters useless.
Almost every organization is at risk of being targeted by this kind of campaign, even if the one analyzed by Talos seems to focus on North America, Singapore and Italy. It might be just a question of the wording and language used in the phishing emails being more successful in the affected regions.
As the usual prevention methods are diminished with this campaign, organizations need to improve their abilities to detect the activity of attacker that happen in the third stage of a malware attack: ‘get ready’.
Talos’ analysis describes in detail the methods used to connect to the cloud instances and download additional resources from them. That resource, known as remote access trojan, RATs, namely NanoCore, NetWire or AsyncRAT is downloaded using Powershell commands, which marks the first detection point to keep an eye on. Any use of Powershell by a regular user should be monitored, if not disabled by group policy security settings.
If such activity is detected, an organization can execute on pre-defined remediation steps like roll backs or it can quarantine the affected system to prevent further spread. Should that not be in place, the following downloads and change in registry setting related to those RAT malware strains can be detected using a file integrity monitoring solution.
This will impact the attacker move to stage 4 of a malware campaign, which is to ‘get more’ information. Once a malware has established its foothold in stage 3 it will roam around to find additional information, steal credentials or valuable data and further map out the infrastructure. Being in this last stage before attackers start to encrypt or exploit their victims can be prevented and remediated using thorough AD security and data access governance solutions.
This campaign also shows an initial confirmation of one of highlighted cyber security trends for 2022 that attackers will use hijacked infrastructure like unmanaged devices in home networks, being much easier to infect with malicious software than a professionally secured enterprise IT environment. With processing power and bandwidth connectivity in residences increasing, home networks will become more attractive to bad actors.
For example, by infecting many devices, they will be able to change IP addresses or even domain names dynamically during malware campaigns, thwarting common defenses like IP blocking and DNS filtering. IT teams should keep this new threat vector in mind when reviewing their security strategies and incident response plans as described above. Moreover, the IT industry should seek to increase user awareness and best practices adoption to reduce the number of ‘easy victims’.