During a recent incident response (IR) engagement, the Unit 42 team identified that the Vice Society ransomware gang exfiltrated data from a victim network using a custom built Microsoft PowerShell (PS) script. We’ll break down the script used, explaining how each function works in order to shed light on this method of data exfiltration.

Ransomware gangs use a plethora of methods to steal data from their victims’ networks. Some gangs bring in outside tools, including tools such as FileZilla, WinSCP and rclone. Other gangs use living off the land binaries and scripts (LOLBAS) methods, such as PS scripts, copy/paste via Remote Desktop Protocol (RDP) and Microsoft’s Win32 API (e.g., Wininet.dll calls). Let’s examine what happens when a PS script is used to automate the data exfiltration stage of a ransomware attack.

A ransomware victim called in the BlackBerry Incident Response (IR) team during this year’s 4th of July holiday weekend. We quickly realized we were investigating an attack by a previously unknown group, calling themselves “MONTI.” They encrypted nearly 20 user hosts along with a multi-host VMware ESXi cluster that brought down over 20 servers.

Threat research shows that the only credible reference of the “Monti” ransomware group prior to today was a tweet from security researchers at MalwareHunterTeam, posted on June 30, 2022. The Twitter post mentioned the possibility that Monti ransomware may have had “5-10 victims in the past months,” though no data is publicly available on these victims.

Most Indicators of Compromise (IOCs) identified by the BlackBerry IR team in the Monti attack were also seen in previous Conti ransomware cases — except one: Monti threat actors leveraged the Action1 Remote Monitoring and Maintenance (RMM) agent.

This article provides a general overview of the incident, denotes the unique characteristics of this “new” threat actor group, and includes malware analysis of the payload used. We also include a breakdown of “Veeamp,” a password stealer malware targeting the Veeam data backup application, which was identified during the incident.