The BlackCat/ALPHV Ransomware Gang's Attack on Pretzel-Stouffer

The BlackCat/ALPHV ransomware gang has attacked Pretzel-Stouffer. Pretzel & Stouffer, Chartered, often referred to as Pretzel-Stouffer, is a law firm based in Chicago, Illinois, USA. The firm is known for its legal expertise and services in various practice areas, including litigation and dispute resolution. BlackCat/ALPHV posted Pretzel-Stouffer to its data leak site on September 25th, claiming to have stolen 736GB of company data.

Overview of BlackCat/ALPHV Ransomware

First observed in late 2021, BlackCat/ALPHV is a RaaS (Ransomware-as-a-Service) that employs a well-developed RaaS platform that encrypts by way of an AES algorithm. The code is highly customizable and includes JSON configurations for affiliate customization. BlackCat/ALPHV has the ability to disable security tools and evade analysis and is probably the most advanced ransomware family at present capable of employing different encryption routines, advanced self-propagation, and hinders hypervisors to for obfuscations and anti-analysis.

BlackCat/ALPHV can impact systems running Windows, VMWare ESXi, and Linux (including Debian, ReadyNAS, Ubuntu, and Synology distributions). BlackCat/ALPHV became one of the more active RaaS platforms over the course of 2022, and attack volumes in Q1 2023 continued to increase although it was overtaken by Cl0p in number of attacks in Q1 2023.

Ransom Demands and Techniques

BlackCat/ALPHV typically demands ransoms in the $400,000 to $3 million range but has exceeded $5 million. BlackCat/ALPHV is the first ransomware group using Rust, a secure programming language that offers exceptional performance for concurrent processing. The ransomware deletes all Volume Shadow Copies using the vssadmin.exe utility and wmic to thwart rollback attempts and attains privilege escalation by leveraging the CMSTPLUA COM interface and bypasses User Account Control (UAC). It encrypts files with the ChaCha20 or the AES algorithm. BlackCat/ALPHV developers opted for faster over stronger encryption by employing several modes of intermittent encryption and employs a tool called Exmatter for data exfiltration.

Targeting and Impact

BlackCat/ALPHV has wide variability in targeting, but most often focuses on the healthcare, pharmaceutical, financial, manufacturing, legal, and professional services industries. The group achieved a new low by publishing private, compromising clinical photographs of breast cancer patients exfiltrated during an attack. BlackCat/ALPHV also exfiltrates victim data prior to the execution of the ransomware – including from cloud-based deployments - to be leveraged in double extortion schemes to compel payment of the ransom demand. They have one of the more generous RaaS offerings, offering as much as 80-90% cut to affiliates. BlackCat/ALPHV is also noted for putting their leaks website on the public web instead of the dark web.