Search This Blog

Powered by Blogger.

Blog Archive

Labels

Footer About

Footer About

Labels

Showing posts with label Ransomware Attacks. Show all posts

New Ransomware Targets AI Model Weights but Fails to Collect Ransom


An updated ransomware campaign is targeting an important but often overlooked asset in artificial intelligence environments: trained AI models and their supporting data. Researchers have discovered a ransomware strain that encrypts AI model weights, vector indexes, and training data, but no ransom payment mechanism appears to have been established. 


The Threat Research Team at Sysdig attributed the activity to the threat actor JADEPUFFER, who previously compromised the same internet-facing Langflow server. This attack exploited the critical vulnerability CVE-2025-3248 that allows remote Python code execution due to a critical missing authentication vulnerability in Langflow's code-validation endpoint. 

Although Langflow fixed the vulnerability in version 1.3.0, the targeted server remained vulnerable even after it was publicly reported. An ENCFORGE binary was deployed in the second campaign that searched for 180 different file extensions using a compiled Go-based ransomware binary. As opposed to conventional ransomware that may incidentally encrypt model files, ENCFORGE identifies AI-related assets specifically, including PyTorch and TensorFlow checkpoints, Hugging Face SafeTensors weights, GGUF files for large language models within the local region, FAISS vector indexes, as well as training data stored in Parquet and NumPy formats. 

During the second campaign, ENCFORGE was deployed, a Go binary powered by UPX that searches for 180 file extensions across a wide range of machine-learning applications. In contrast to conventional ransomware, which may encrypt model files incidentally, ENCFORGE is specifically designed to identify AI-related assets, such as PyTorch and TensorFlow checkpoints, Hugging Face SafeTensor weights, GGUF files associated with local large language models, FAISS vector indexes, Apache Parquet and TFRecord training datasets, and NumPy arrays, among others. 

A command-line interface for adding custom file extensions has been provided by attackers, along with examples of LoRA fine-tuning adapters and legacy GGML weights, further demonstrating that the malware was specifically designed for artificial intelligence environments. According to researchers, the ransomware encrypts portions of files with AES-256-CTR encryption keys protected by embedded RSA-2048 keys, although there appears to be no network functionality to facilitate data theft or ransom collections. 

ENCFORGE was not identified by Sysdig as a leak site, outbound communication, or payment portal. Instead of a Proton Mail address in the ransom note, a Proton Mail address was included, suggesting that the operation was primarily oriented toward rendering the victim's AI assets useless, rather than stealing them to conduct double extortion. ENCFORGE differs from double-extortion ransomware by lacking an exfiltration mechanism.

A leak site and functional capability for stealing and publishing victim data were not discovered by researchers. Instead, the primary objective of the campaign is to destroy AI assets by rendering model files and related data unusable. JadePuffer's earlier campaign also included a contact address that corresponded to the malware, indicating that this campaign is related to JadePuffer. 

Due to the fundamental difference between restoring a trained AI model and restoring a conventional database, the potential impact is significant. Sysdig estimates that it could cost between $75,000 and $500,000 to rebuild a production-ready fine-tuned model directly, depending on GPU resources and engineering efforts. If training data is compromised, recovery becomes even more challenging. 

Model artifacts and associated training data are particularly difficult to recover when the system hosting them contains both. In this case, restoring the model may not be possible until the dataset has been recovered and the necessary training processes have been repeated. Because organizations often maintain multiple model variants on shared storage, one encryption event can have a significant impact on several production or development assets concurrently. 

It is also evidenced in the campaign that attackers are increasingly adapting their attacks around artificial intelligence infrastructure. The attacker generated multiple Python scripts using the compromised Langflow environment, as the ransomware could not initially be downloaded from the command-and-control server. During the first five minutes, the scripts were able to develop a method for exiting the container environment through the exposed Docker socket and executing the ransomware on the host machine. 

Rapid escalation is a result of broader trends in ransomware operations in which attackers are increasing the speed at which they can gain access and deploy ransomware. As a result of the JadePuffer incident, the delivery mechanism was rebuilt within minutes after the original download failed, leaving little time to detect and contain the intrusion before it began encryption. Six Python scripts progressively refined the escape procedure during the escape process. 

By launching a privileged container over the mounted Docker socket, the ransomware was moved across the container boundary through the host's proc file system and executed against the host file system outside the original container's isolation using the mounted Docker socket. Following encrypting the targeted files, ENCFORGE terminated processes holding file locks and deleted itself once the encryption was complete. The incident highlighted an increasing security vulnerability in the AI asset ecosystem. 

The backups should be separated from the systems that host production models to ensure that a compromise of the artificial intelligence environment does not also compromise the recovery copies. Organizations should ensure model checkpoints, vector indexes, and training data are backed up in immutable, tested versions, remove unnecessary Docker sockets, rotate credentials that are accessible from compromised systems, and monitor for mass encryption of AI-specific files. 

In response to the increasing value of artificial intelligence models in businesses, ransomware operators have begun targeting the files containing the accumulated work behind the systems. As a result of the ENCFORGE campaign, AI infrastructure must now be protected as critical assets rather than as ordinary files, by treating model weights and associated datasets accordingly.

Among other things, ENCFORGE emphasizes the importance of treating artificial intelligence model weights, training data, and related artifacts as critical digital assets for organizations. In order to limit the impact of future attacks, it will be necessary to protect these assets with isolated backups, enhanced access controls, and timely vulnerability remediation. As attackers increasingly tailor ransomware to emerging technologies, it is imperative to protect these assets.

Ransomware Campaign Leverages QEMU to Slip Past Enterprise Defences


 

In an effort to circumvent traditional security controls, hackers are increasingly relying on virtualisation as a covert execution layer, embedding malicious operations within QEMU environments. As observed in observed incidents, adversaries deployed concealed virtual machines in which tooling and command execution occurred largely beyond the detection range of endpoint detection systems, leaving minimal forensic artifacts on the operating system. 

In most cases, these environments are introduced as virtual disk images disguised under atypical file extensions such as .db or .dll and triggered by scheduled tasks with SYSTEM level privileges to create a parallel runtime that blends with legitimate processes.

According to analysts at Sophos, such techniques take advantage of the trust associated with widely used virtualization software. This pattern extends to platforms such as Microsoft Hyper-V, Oracle VM VirtualBox, and VMware, among others. These tactics reflect a broader strategic shift in which legitimate infrastructure is used to create isolated, low-noise environments that allow ransomware deployment while retaining effective anonymity to host-based defenses. Based on this pattern, researchers at Sophos have highlighted that QEMU misuse is not a recent development, but its resurgence in recent operations signals a renewed tactical emphasis on the use of QEMU. 

In late 2025, analysts have identified two separate ransomware campaigns, STAC4713 and STAC3725, which use virtualised environments to avoid detection, and STAC4713 is specifically associated with the financial-motivated PayoutsKing cluster of ransomware activities. 

An attacker established persistence for this campaign by creating a scheduled task, “TPMProfiler,” which executed a concealed virtual machine with SYSTEM-level privileges. A disk image deployment was implemented in which benign assets were deliberately disguised as benign assets, initially appearing as database files, but later taking on the appearance of dynamic link libraries in order to blend seamlessly into routine system artifacts. 

Once active, the virtual instance initiated reverse SSH tunneling mechanisms and port-forwarding mechanisms, forming covert communication channels that enabled sustained remote access while remaining outside the scope of conventional monitoring tools. 

During this isolated Alpine Linux environment, adversaries employed a compact toolkit that enabled tunneling, obfuscation, and data exfiltration, facilitating credential harvesting, the extraction of Active Directory databases, as well as the lateral exploration of network shares, all by utilizing legitimate system utilities. 

By integrating trusted binaries and hidden virtual infrastructure, this intentional convergence highlights a refined intrusion model where malicious activity is woven into normal system behavior, increasing the difficulty of detecting and responding to intrusions. 

A further investigation of STAC4713 has revealed its origin dates are November 2025, when it has been associated with the GOLD ENCOUNTER threat group and directly associated with PayoutsKing ransomware, a ransomware operation that differs from the conventional ransomware-as-a-service environment by executing intrusions without the assistance of affiliates. 

After emergence in mid-2025, the group has demonstrated a focus on hypervisor-centric environments, developing customized encryption tools for platforms such as VMware and VMware ESXi, signaling a deliberate shift towards infrastructure-level disruption. 

Additionally, a second campaign, STAC3725, appeared in February 2026. This campaign accessed the system via the CVE-2025-5777 exploit chain before deploying a malicious instance of ConnectWise ScreenConnect to secure persistence. Using this foothold, attackers orchestrated credential harvesting against Active Directory environments using a concealed QEMU virtual machine. 

The intrusion sequence in STAC4713 is well-planned, beginning with the creation of the “TPMProfiler” scheduled task which executes qemu-system-x86_64.exe with SYSTEM privileges. As a result, the boot-up of a virtual hard drive image disguised as benign files  initially "vault.db" and later renamed "bisrv.dll" -- was used to evade scrutiny.

In addition to this obfuscation, network manipulation techniques are employed, including port forwarding from non-standard ports such as 32567 and 22022 to SSH port 22, while reverse tunnels involving AdaptixC2 or OpenSSH are used to maintain persistent and covert connectivity to attacker-controlled networks. Embedded virtual machines operate on Alpine Linux 3.22.0 images preconfigured to offer a compact but robust toolkit that enables the rapid transfer of data and execution of commands. 

The toolkit includes Linker2, AdaptixC2, WireGuard's WireGuard Obfuscation Layer (wg-obfuscator), BusyBox, Chisel, and Rclone. In contrast, STAC3725 utilizes a more adaptive approach, compiling its toolset within a virtual environment in situ, including frameworks such as Impacket, KrbRelayX, Coercer, BloodHound.py, NetExec, Kerbrute, and Metasploit, as well as Python, Rust, Ruby, and C dependencies. 

Post-compromise activities include credential extraction, Kerberos user enumeration via Kerbrute, Active Directory reconnaissance via BloodHound, and payload staging over FTP channels, demonstrating a methodical and deeply embedded attack model in which virtualization serves not only as a concealment mechanism, but also as a platform for sustained intrusion. 

In sum, STAC4713 and STAC3725's activity indicate a calculated evolution in adversary tradecraft where virtualisation is no longer just a peripheral tactic for evasion but rather a critical component of adversary operations. A malicious workflow may be embedded within QEMU instances and aligned with trusted system processes, thus decoupling attackers' activities from the host environment. 

As a result, conventional endpoint controls will be unable to detect the attacker's activities while maintaining persistent, low-noise access. By employing disguised storage artifacts, executing tasks at the SYSTEM level, and utilizing encrypted communication channels, a disciplined approach to stealth is demonstrated, while the integration of credential harvesting, Active Directory reconnaissance, and lateral movement capabilities highlights the end-to-end nature of the intrusion. 

Sophos has observed that the resurgence of such campaigns indicates a broader industry challenge, in which legitimate infrastructure and administrative tools are increasingly repurposed to undermine defensive assumptions. 

Virtualised attack frameworks, with their convergence of concealment, persistence, and operational depth, provide a formidable vector for modern ransomware operations, requiring an extension of detection strategies beyond the host to virtual layers where adversaries are actively exploiting these vulnerabilities.