Heads up: risk actors at the moment are deploying a Go-language implementation of Cobalt Strike known as Geacon that first surfaced on GitHub 4 years in the past and had remained largely below the radar.
They’re utilizing the red-teaming and attack-simulation instrument to focus on macOS programs in a lot the identical approach they’ve used Cobalt Strike for post-exploit exercise on Home windows platforms the previous few years.
Safety researchers at SentinelOne reported the exercise this week after recognizing a number of Geacon payloads showing on VirusTotal in latest months. SentinelOne’s evaluation of the samples confirmed some have been possible associated to reputable enterprise red-team workouts, whereas others gave the impression to be artifacts of malicious exercise.
One malicious pattern submitted to VirusTotal on April 5 is an AppleScript applet titled “Xu Yiqing’s Resume_20230320.app” that downloads an unsigned Geacon payload from a malicious server with a China-based IP tackle.
SentinelOne discovered the appliance is compiled for macOS programs operating on both Apple or Intel silicon. The applet comprises logic that helps it decide the structure of a selected macOS system so it might probably obtain the particular Geacon payload for that system. The compiled Geacon binary itself comprises an embedded PDF that first shows a resume for a person named Xu Yiqing earlier than beaconing out to its command and management (C2) server.
“The compiled Geacon binary has a large number of capabilities for duties similar to community communications, encryption, decryption, downloading additional payloads, and exfiltrating knowledge,” SentinelOne mentioned.
In one other occasion, SentinelOne found a Geacon payload embedded in a pretend model of the SecureLink enterprise remote-support software. The payload appeared in VirusTotal on April 11 and focused solely Intel-based macOS programs. Not like the earlier Geacon pattern, SentinelOne discovered the second to be a bare-bones, unsigned software possible constructed with an automatic instrument. The app required the person to grant entry to the system digital camera, microphone, administrator privileges, and different settings sometimes protected below macOS’s Transparency, Consent, and Management framework. On this occasion, the Geacon payload communicated with a recognized Cobalt Strike C2 server with an IP tackle primarily based in Japan.
“This isn’t the primary time we have now seen a Trojan masquerading as SecureLink with an embedded open-source assault framework,” SentinelOne mentioned. The safety vendor pointed to its discovery final September of an open-source assault framework for macOS known as Sliver embedded with a pretend SecureLink as one other instance. “[Its] a reminder to all that enterprise Macs at the moment are being broadly focused by quite a lot of risk actors,” SentinelOne mentioned.
Attackers have lengthy used Cobalt Strike for quite a lot of malicious post-exploit actions on Home windows programs together with for establishing command-and-control, lateral motion, payload technology, and exploit supply. There have been cases the place attackers have sometimes used Cobalt Strike to focus on macOS as effectively. One instance is a typosquatting assault final yr the place a risk actor tried to deploy Cobalt Strike on Home windows, Linux, and macOS programs by importing a malicious bundle dubbed “pymafka” to the PyPI register.
In different cases, attackers have additionally used a macOS targeted red-teaming instrument known as Mythic as a part of their assault chains.
The exercise involving Geacon itself began shortly after an nameless Chinese language researcher utilizing the deal with “z3ratu1” launched two Geacon forks final October — one personal and certain on the market known as “geacon_pro” and the opposite public, known as geacon-plus. The professional model consists of some extra options like anti-virus bypassing and anti-kill capabilities, says Tom Hegel, senior risk researcher at SentinelOne.
He ascribes the sudden attacker curiosity in Geacon to a weblog that z3ratu1 posted describing the 2 forks and his makes an attempt to market his work. The unique Geacon mission itself was largely for protocol evaluation and reverse engineering functions, he says.
The rising malicious use of Geacon matches in with a broader sample of rising attacker curiosity in macOS programs.
Earlier this yr, researchers at Uptycs reported on a novel new Mac malware pattern dubbed “MacStealer” that, consistent with its identify, stole paperwork, iCloud keychain knowledge, browser cookies, and different knowledge from Apple customers. In April, the operators of “Lockbit ” turned the primary main ransomware actor to develop a Mac model of their malware, setting the stage for others to comply with. And final yr, North Korea’s infamous Lazarus Group develop into among the many first recognized state-backed teams to start concentrating on Apple Macs.
SentinelOne has launched a set of indicators to assist organizations determine malicious Geacon payloads.