![]() ![]() ![]() Gustavo Palazolo, Staff Threat Research Engineer at Netskope also had some useful tips and tool suggestions, noting “Using the Pyramid of Pain concept, we can start by blocking known IOCs from Cobalt Strike through threat intelligence feeds, like ThreatFox and MalwareBazaar. For example, observing a DLL loaded from a suspicious path such as %Temp% would be highly unusual for most environments.” Detecting Cobalt Strike: Beware"rundll32.exe" instances that. Monitor file paths associated with DLLs being executed by rundll32.exe. "Additional operators can enable adversaries to modify or acquire files, or even execute arbitrary code such as Javascript. Familiarise yourself with the command line operators that adversaries can invoke in a malicious rundll32.exe function call. Inspecting file changes made by these utilities is also a great way to check for possible malicious use of signed binaries. Remain alert to instances of productivity applications interacting suspiciously with system processes, as adversaries may inject a phishing payload into rundll32.exe. Although this prefix is configurable, we have observed adversaries leverage the default configuration in multiple incident response engagements," he noted.Ĭrowdstrike's Meyer added that defenders can also make sure they “maintain a baseline of 'known good' command line arguments, especially those associated with signed binaries such as installutil.exe, msbuild.exe, mshta.exe and rundll32.exe. With the default configuration that command prefix is powershell -nop -exec -bypass -EncodedCommand. "The majority of PowerShell Engine Startup events generated by Cobalt Strike will have the HostApplication field begin with a command prefix. These measures can aid in detecting Cobalt Strike. Additionally, upgrade to the most recent version of PowerShell and disable previous versions, as PowerShell is backward compatible. He added: “Due to the high prevalence of Cobalt Strike in contemporary intrusions it’s wise to collect EID 400 (PowerShell Engine Startup) and EID 7045 event logs (Service Installation) for monitoring and alerting in a centralised SIEM platform. See also: From C2 to C3: Hackers are getting esoteric at exfiltration The most widely seen APT tools and techniques in Q3 2021: Trellix These insights can be used to impose an operational cost on the adversary by blocking the C2 at the perimeter,” said Meyers in an emailed comment to The Stack. Armed with this information, analysts may use tools like Didier Stevens’ 1768.py to pull licensing and embedded C2 configuration from decoded beacons. Cryptographic and fuzzy hashing can be used to gain an idea of the type of threat faced like the malware family responsible. “When uncovering suspicious activity, open source intelligence can often be a source of invaluable information and can prevent your team from recreating work already produced by other malware analysts. ![]() Adversaries often install tooling such as Cobalt Strike for establishing an initial foothold, and post-exploitation activities including command and control and lateral movement… We asked some experienced security folks for their tips on detecting Cobalt Strike.ĬrowdStrike's Adam Meyers, who leads the Threat Intelligence line of business for the company, noted: “Its client agent, ‘Beacon’, is executed in the memory space of a compromised system and leaves minimal on-disk footprints. While prevention of intrusion is, of course, better than cure – identify your assets, patch them religiously, enforce MFA, restrict credentials, reduce AD attack paths, kill off those unused and poorly protected VPN accounts - detecting Cobalt Strike is Good Medicine and more attention needs to be on doing so. Its ubiquity is such that in late 2021 it even emerged Emotet malware now installs Cobalt Strike “beacons” (its payload to model an advanced actor, which executes PowerShell scripts, logs keystrokes, spawns other payloads, etc.). The product now has a full research and development team behind it – and hackers can’t get enough of it: Blue Teams need to pay close attention. The “threat emulation” framework ($3,500 per user for a year’s license, if bought commercially from owner Help Systems) was first released in 2012 by creator Raphael Mudge, who led its development until March 2021. Secureworks meanwhile found Cobalt Strike playing a role in 19% of the network intrusions it investigated in 2021. Cobalt Strike was the single most widely seen offensive tool used by Advanced Persistent Threat (APT) actors in the last quarters of 2021, according to analysis by security firm Trellix. ![]()
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