![]() Consequently, this stage of an attack is completely hidden from antivirus solutions that do not scan device memory.Īs noted, don't rely on a Cobalt Strike beacon signature for stopping future attacks using a modified version of the beacon. Critically, the stagers (programs that can be used to download sections of the Beacon payload) that Cobalt Strike uses to download the Beacon payload deploy mostly in device memory. As a result, threat actors can configure Cobalt Strike to blend in with background noise, making traffic-based detection far more difficult. This feature of the Cobalt Strike platform called “Malleable C2” allows attackers to adapt command and control traffic (C2) to the kind of legitimate traffic that is likely to come from an uncompromised victim device. The reason why is simple: the way in which Cobalt Strike conducts network egress is highly customizable and capable of mimicking traffic from legitimate applications. With Cobalt Strike payloads uniquely generated for specific victims and hidden within innocent processes and applications, antivirus solutions that rely on recognizable malicious signatures cannot see or stop them.īecause Cobalt Strike shellcode can move via the named pipes used for inter-process communication within Windows and Unix machines, malicious shellcode will remain invisible even when an antivirus or endpoint detection and response ( EDR) solution uses a sandbox - unless it is configured to emulate named pipes (which is rare).Īlthough Cobalt Strike is a command and control (C2) framework, which means that attacks rely on attackers establishing communication with clients installed on targeted machines, analyzing network traffic is not a reliable way of finding and stopping Cobalt Strike Beacons. While some Cobalt Strike attacks can involve executables such as DLL files or libraries being installed on a targeted endpoint, most work by injecting malicious shellcode into legitimate processes. The goal for any Cobalt Strike attack is the deployment of a post-exploitation payload, known as a “Beacon,'' onto a compromised endpoint. Looks like ESET doesn't even trust their competitor. docx file via Winword.Īll samples were discovered by Dr.Web. As such, it could have detected it trying to open the. Note that Eset sets a deep behavior inspection hook i.e.dll, into cmd.exe. Let's refer to a specific example using this prior posted sample. That is the malware won't perform any malicious activities. Also if the malware is run in a local sandbox, VM, etc., that doesn't prove anything since malware these days increasingly deploy anti-sandbox, VM, etc. The only way to fully known if the malware is not actually detected at some stage is to run it. ![]() It needs be noted that Eset sample detection at VT needs to be taken "with a grain of salt" as I have stated numerous times in this forum.Īll Eset employs protection-wise at VT is static signature detection for the most part. ĭue to the lack of response, I felt it necessary to highlight these samples here. The tracking numbers for those reports are, ,, ,, ,, and. Additionally, most samples remain undetected. I intended to report these via your email channel, but my recent submissions on, , and received no feedback. I hope ESET can consider enhancing signatures to address such threats more effectively. ![]() Given the frequency of these misses, it's alarming. Below are VT links for some of the undetected samples: I've noticed that many CobaltStrike backdoor samples seem to bypass ESET's detection.
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