SysJoker was first discovered during an active attack on a Linux-based web server of a leading educational institution.
After further investigation, Intezer found that SysJoker also has Mach-O and Windows PE versions.
Based on Command and Control (C2) domain registration and samples found in VirusTotal, they estimate that the SysJoker attack was initiated during the second half of 2021.
SysJoker masquerades as a system update and generates its C2 by decoding a string retrieved from a text file hosted on Google Drive.
During the analysis the C2 changed three times, indicating the attacker is active and monitoring for infected machines.
Based on victimology and malware’s behavior, they assess that SysJoker is after specific targets.
SysJoker was uploaded to VirusTotal with the suffix .ts which is used for TypeScript files.
A possible attack vector for this malware is via an infected npm package.
The malware is written in C++ and each sample is tailored for the specific operating system it targets. Both the macOS and Linux samples are fully undetected in VirusTotal.
SysJoker’s behavior is similar for all three operating systems.
Unlike Mac and Linux samples, the Windows version contains a first-stage dropper.
The dropper (d71e1a6ee83221f1ac7ed870bc272f01) is a DLL that was uploaded to VirusTotal as style-loader.ts.
The Dropper drops a zipped SysJoker (53f1bb23f670d331c9041748e7e8e396) from C2 https[://]github[.]url-mini[.]com/msg.zip, copies it to C:ProgramDataRecoverySystemrecoveryWindows.zip, unzips it and executes it. All of these actions are executed via PowerShell commands.
Sign Up For Threat Alerts
Jul 04, 2023
Rhysida Ransomware RaaS Crawls Out of Crimeware...
The Rhysida ransomware-as-a-service (RaaS) group has gone from a dubious newcomer to a fully-fledged ransomware...
Jun 26, 2023
Operation Magalenha – Long-Running Campaign Pursues Portuguese...
The attackers can steal credentials and exfiltrate users' data and personal information, which can be...
Apr 24, 2023
Lazarus Group Adds Linux Malware to Arsenal...
Researchers have discovered a new campaign conducted by Lazarus, known as "Operation DreamJob," which targets...
Apr 23, 2023
Additional IOCs for 3cx breach
Recently an unexpected malicious activity emanating from a legitimate, signed binary, 3CXDesktopApp was observed.
Apr 23, 2023
Ex-Conti and FIN7 Actors Collaborate with New...
IBM Security X-Force recently discovered a new malware family Analysts have called "Domino," which Analysts...
Apr 20, 2023
AuKill EDR killer malware abuses Process Explorer...
The AuKill tool abuses an outdated version of the driver used by version 16.32 of...
Apr 20, 2023
Fake Chrome updates spread malware
A campaign running since the end of last year is using hacked sites to push...
Apr 20, 2023
QBot using new attack vector in its...
QBot, also known as QakBot, previously operated as a banking trojan and has since transformed...
Apr 20, 2023
CrossLock Ransomware Emerges: New Golang – Based...
The CrossLock ransomware employs the double extortion technique to increase the likelihood of payment from...
Apr 20, 2023
Windows Zero-Day Vulnerability CVE-2023-28252 Exploited by Nokoyawa...
A zero-day vulnerability in the Microsoft Windows system, which also affects Windows 11, has been...
Apr 18, 2023
Additional IOcs for 3cx breach
Recently an unexpected malicious activity emanating from a legitimate, signed binary, 3CXDesktopApp was observed. As...
Apr 18, 2023
Additional IOcs for 3cx breach
Recently an unexpected malicious activity emanating from a legitimate, signed binary, 3CXDesktopApp was observed. As...
Apr 18, 2023
APT36 Expands Interest Within Indian Education Sector
Symantec described UPS in 2016 report as Buckeye (also known as APT3 Gothic Panda UPS...
Apr 17, 2023
ChinaZ DDoS Bot Malware Distributed To Linux...
The ChinaZ DDoS bot malware was discovered targeting Linux systems while a version for Microsoft...
Apr 16, 2023
Resurgence Of The Mexals Cryptojacking Campaign
The Mexals crypto jacking campaign has been in operation since at least 2021 and continues...