Sload (also termed as Starslord loader) has proven to be one of the most destructive malware variants in recent years. It usually acts as a downloader, which is a computer virus that accumulates and exfiltrates data from an infected system in order to analyze the target and drop a more significant payload if the target is profitable.
Sload has been active in Europe since at least 2018, with numerous vendors reporting assaults on targets in the United Kingdom and Italy. Instead of employing an executable or a malicious document to invade devices, the malware's developers have chosen to use scripts that are intrinsic to Windows operating systems such as VBS and PowerShell as an initial foothold, tricking users into executing them using spear phishing.
The downloader is undergoing development and has gone through several iterations; the creator is continuously changing the first stage script but the main module remains basically unchanged.
According to early reports, this virus downloads a PowerShell script, which then downloads and executes Sload, using a rogue LNK file (Windows shortcut). Later editions start with obfuscated WSF/VBS scripts that are frequently mutated to avoid detection by anti-virus software. The initial script used in attacks has a low VirusTotal score and is meant to get beyond complex security technologies like EDRs.
This year, Minerva Labs has noticed Sload infections arriving from Italian endpoints. The script they found is an obfuscated WSF script that decodes a sequence of malicious commands and then secretly downloads and runs a remote payload in memory after being executed.
The script does this by renaming legal Windows binaries, which is a straightforward evasion method. Both "bitsadmin.exe" and "Powershell.exe" are copied and renamed, with the former being used to download a malicious PowerShell script and the latter loading it into memory and executing it.
The downloader's final payload varies, but it has been known to drop the Ramnit and Trickbot banking trojans, both of which are extremely dangerous malware that can lead to ransomware attacks.