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
Mar 21, 2023
Dotrunpex – Demystifying new virtualized .net injector...
DotRunpeX is a new injector written in .NET using the Process Hollowing technique and used...
Mar 21, 2023
GlobeImposter Ransomware With MedusaLocker Spreading Via RDP
A GlobeImposter ransomware campaign was discovered being carried out by the attackers behind MedusaLocker. The...
Mar 20, 2023
Common credential stealers
FortiGuard Threat Research has observed an increasing threat arising from credential stealers. The most common...
Mar 20, 2023
Sirattacker And ALC Ransomware Analysis
The Sirattacker and ALC ransomware families continue to gain traction and compromise Microsoft Windows devices....
Mar 19, 2023
Google Advertising Used To Distribute RedLine Stealer
A malvertising campaign was discovered mimicking websites belonging to well-known software such as Notepad++ and...
Mar 16, 2023
Microsoft Outlook Elevation of Privilege Vulnerability Exploit
Microsoft has posted a security vulnerability CVE-2023-23397, exploiting it allows attackers to gain elevated privileges...
Mar 16, 2023
ImBetter Information Stealer Targets Cryptocurrency Users
Threat actors are targeting cryptocurrency users with the ImBetter information stealer malware. Adversaries are hosting...
Mar 16, 2023
ImBetter Information Stealer Targets Cryptocurrency Users
Threat actors are targeting cryptocurrency users with the ImBetter information stealer malware. Adversaries are hosting...
Mar 15, 2023
US Cert Alert – Threat Actors Exploit...
CISA and authoring organizations assess that, beginning as late as November 2022, threat actors successfully...
Mar 15, 2023
Threat Actors Use ParallaxRAT For Targeting Cryptocurrency...
Threat actors are targeting organization in the cryptocurrency sector with spam and phishing campaigns that...
Mar 13, 2023
Exposing The Lazarus Arsenal WinorDLL64 Backdoor
In 2021 the researchers discovered and dissected a tool from the Lazarus APTs arsenal named...
Mar 12, 2023
Clasiopa New Group Targets Materials Research
A campaign targeting the materials research sector with custom and commodity utilities and malware is...
Mar 09, 2023
New Emotet campaign
Emotet is a type of malware that is designed to steal sensitive information from infected...
Mar 09, 2023
How sys01 stealer will get your sensitive...
Morphisec has been tracking an advanced info stealer Analysts have named "SYS01 stealer." SYS01 stealer...
Mar 09, 2023
How sys01 stealer will get your sensitive...
Morphisec has been tracking an advanced info stealer Analysts have named "SYS01 stealer." SYS01 stealer...