The Play ransomware group is using two new, custom-developed tools that allow it to enumerate all users and computers on a compromised network, and copy files from the Volume Shadow Copy Service (VSS) that are normally locked by the operating system.
The first tool found by researchers at Symantec, by Broadcom Software, was Grixba (Infostealer.Grixba), which is a network-scanning tool used to enumerate all users and computers in the domain.
The threat actors use the .NET infostealer to enumerate software and services via WMI, WinRM, Remote Registry, and Remote Services. The malware checks for the existence of security and backup software, as well as remote administration tools and other programs, saving the gathered information in CSV files that are compressed into a ZIP file for subsequent manual exfiltration by the threat actors.
The Play ransomware gang developed Grixba using Costura, a popular.NET development tool for embedding an application's dependencies into a single executable file. This eliminates the requirement for the program and its dependencies to be deployed separately, making it easier to share and deploy the application. Costura embeds into applications the DLL file costura.commandline.dll, which is used by Grixba to parse command lines.
An analysis of a Grixba sample by Symantec revealed the following help message and functionality:
The Scan mode enumerates software and services via WMI, WinRM, Remote Registry, and Remote Services.
It then checks for the existence of the following security programs:
- Symantec Endpoint Protection
- Carbon Black
It also checks for the existence of the following backup software:
It then checks for the existence of the following remote administration tools:
- GoTo Resolve
- Splashtop SOS
- Remote Desktop Manager
- Kaseya VSA
- Remote Utilities
Finally, it checks for the existence of the following programs:
- Hitachi Storage Navigator Modular
The malware then saves all the information in CSV files and, using WinRAR, compresses them to a file named export.zip.
List of CSV files compressed by Grixba:
Scanall mode is similar to Scan mode, but scans for a broader list of programs.
Clr mode deletes the logs from local and remote computers. It also enumerates the following registry keys:
It uses the APIs "EvtOpenLog" and "EvtClearLog" to delete the logs and deletes the WMI activity logs from the event source "Microsoft-Windows-WMI-Activity".
VSS Copying Tool
The Play ransomware gang was also recently observed using another .NET executable, which was also developed with the Costura tool.
Costura embeds the library AlphaVSS into executables. The AlphaVSS library is a.NET framework that provides a high-level interface for interacting with VSS. The library makes it easier for .NET programs to interface with VSS by offering a set of controlled APIs. Developers can use these APIs to generate, manage, and delete shadow copies, as well as access information about existing shadow copies such as size and status.
The tool created by the Play ransomware operators uses AlphaVSS to copy files from VSS snapshots. The tool enumerates the files and folders in a VSS snapshot and copies them to a destination directory. The tool allows the attackers to copy files from VSS volumes on compromised machines prior to encryption. This allows the threat actors to copy files that would normally be locked by the operating system.
Play Ransomware Background
Play ransomware (also known as PlayCrypt), which is developed by a group Symantec tracks as Balloonfly, was launched in June 2022, and since then has been responsible for multiple high-profile attacks. Like most ransomware groups now, Play carries out double-extortion attacks, where the attackers exfiltrate data from victim networks before encrypting them. While the ransomware gang had an initial focus on organizations in Latin America, especially Brazil, it soon widened its targeting.
Play is known for targeting Microsoft Exchange vulnerabilities (CVE-2022-41080, CVE-2022-41082), as well as other flaws, to gain remote code execution (RCE) and infiltrate victim networks. The group was also one of the first ransomware groups to employ intermittent encryption, a technique that allows for faster encryption of victims’ systems. The tactic consists of encrypting only parts of the targeted files' content, which would still render the data unrecoverable.
Play is also notable as it doesn’t appear to operate as a ransomware-as-a-service, with Balloonfly seemingly carrying out the ransomware attacks as well as developing the malware.
Use of Custom Tools on the Rise
Custom tools are increasingly being used by ransomware gangs in their attacks. This is likely due to a number of reasons, such as making attacks more efficient and reducing dwell time. Custom tools can be tailored to a specific target environment, allowing ransomware gangs to carry out attacks faster and more efficiently. The use of proprietary tools also gives ransomware operators more control over their operations. If a tool is widely available, it can be reverse-engineered or adapted by other attackers, potentially weakening the initial attack's effectiveness. By keeping their tools proprietary and exclusive, ransomware gangs can maintain their competitive advantage and maximize their profits.
For the latest protection updates, please visit the Symantec Protection Bulletin.
Indicators of Compromise
If an IOC is malicious and the file available to us, Symantec Endpoint products will detect and block that file.
762bb8a7209da29afb89f7941ae1c00a04cf45a144c6c5dddcfa78ff0d941539 – Play ransomware
86e4e23f9686b129bfb2f452acb16a4c0fda73cf2bf5e93751dcf58860c6598c – SystemBC malware
f706bae95a232402488d17016ecc11ebe24a8b6cb9f10ad0fa5cbac0f174d2e7 – SystemBC malware
c59f3c8d61d940b56436c14bc148c1fe98862921b8f7bad97fbc96b31d71193c – Infostealer.Grixba
453257c3494addafb39cb6815862403e827947a1e7737eb8168cd10522465deb – Infostealer.Grixba
f71476f9adec70acc47a911a0cd1d6fea1f85469aa16f5873dd3ffd5146ccd6b – Infostealer.Grixba
a8a7fdbbc688029c0d97bf836da9ece926a85e78986d0e1ebd9b3467b3a72258 – NetScan
5ef9844903e8d596ac03cc000b69bbbe45249eea02d9678b38c07f49e4c1ec46 – NetScan
f81bd2ac937ed9e254e8b3b003cc35e010800cbbce4d760f5013ff911f01d4f9 – VSS copying tool
367d47ad48822caeedf73ce9f26a3a92db6f9f2eb18ee6d650806959b6d7d0a2 – WinRAR
6f95f7f53b3b6537aeb7c5f0025dbca5e88e6131b7453cfb4ee4d1f11eeaebfc – WinSCP
1409e010675bf4a40db0a845b60db3aae5b302834e80adeec884aebc55eccbf7 – PsExec
137.220[.]49.66 – SystemBC C&C
justiceukraine.com – SystemBC C&C
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