Cybersecurity experts have uncovered a stealthy tactic where attackers bypass Windows defenses by running concealed Linux virtual machines using QEMU. Researchers warn that these hidden environments allow threat actors to maintain persistent access, steal sensitive data, and even deploy ransomware.
A newly identified infostealer called Storm has emerged on underground cybercrime forums in early 2026, signalling a change in how attackers steal and use credentials. Priced at under $1,000 per month, the malware collects browser-stored data such as login credentials, session cookies, and cryptocurrency wallet information, then covertly transfers the data to attacker-controlled servers where it is decrypted outside the victim’s system.
This change becomes clearer when compared to earlier techniques. Traditionally, infostealers decrypted browser credentials directly on infected machines by loading SQLite libraries and accessing local credential databases. Because of this, endpoint security tools learned to treat such database access as one of the strongest indicators of malicious activity.
The approach began to break down after Google Chrome introduced App-Bound Encryption in version 127 in July 2024. This mechanism tied encryption keys to the browser environment itself, making local decryption exponentially more difficult. Initial bypass attempts relied on injecting into browser processes or exploiting debugging protocols, but these techniques still generated detectable traces.
Storm avoids this entirely by skipping local decryption. Instead, it extracts encrypted browser files and quietly sends them to attacker infrastructure, removing the behavioural signals that endpoint tools typically rely on. It extends this model by supporting both Chromium-based browsers and Gecko-based browsers such as Firefox, Waterfox, and Pale Moon, whereas tools like StealC V2 still handle Firefox data locally.
The data collected includes saved passwords, session cookies, autofill entries, Google account tokens, payment card details, and browsing history. This combination gives attackers everything required to rebuild authenticated sessions remotely. In practice, a single compromised employee browser can provide direct access to SaaS platforms, internal systems, and cloud environments without triggering any password-based alerts.
Storm also automates session hijacking. Once decrypted, credentials and cookies appear in the attacker’s control panel. By supplying a valid Google refresh token along with a geographically matched SOCKS5 proxy, the platform can silently recreate the victim’s active session.
This technique aligns with earlier research by Varonis Threat Labs. Its Cookie-Bite study showed that stolen Azure Entra ID session cookies can bypass multi-factor authentication, granting persistent access to Microsoft 365. Similarly, its SessionShark analysis demonstrated how phishing kits intercept session tokens in real time to defeat MFA protections. Storm packages these methods into a commercial subscription service.
Beyond credentials, the malware collects files from user directories, extracts session data from applications like Telegram, Signal, and Discord, and targets cryptocurrency wallets through browser extensions and desktop applications. It also gathers system information and captures screenshots across multiple monitors. Most operations run in memory, reducing the likelihood of detection.
Its infrastructure design adds resilience. Operators connect their own virtual private servers to Storm’s central system, routing stolen data through infrastructure they control. This setup limits the impact of takedowns, as enforcement actions are more likely to affect individual operator nodes rather than the core service.
Storm supports multi-user operations, allowing teams to divide responsibilities such as log access, malware build generation, and session restoration. It also automatically categorises stolen credentials by service, with visible rules for platforms including Google, Facebook, Twitter/X, and cPanel, helping attackers prioritise targets.
At the time of analysis, the control panel displayed 1,715 log entries linked to locations including India, the United States, Brazil, Indonesia, Ecuador, and Vietnam. While it is unclear whether all entries represent real victims or test data, variations in IP addresses, internet service providers, and data volumes suggest ongoing campaigns.
The logs include credentials associated with platforms such as Google, Facebook, Twitter/X, Coinbase, Binance, Blockchain.com, and Crypto.com. Such information often feeds into underground credential marketplaces, enabling account takeovers, fraud, and more targeted intrusions.
Storm is offered through a tiered pricing model: $300 for a seven-day trial, $900 per month for standard access, and $1,800 per month for a team licence supporting up to 100 operators and 200 builds. Use of an additional crypter is required. Notably, once deployed, malware builds continue operating even after a subscription expires, allowing ongoing data collection.
Security researchers view Storm as part of a broader evolution in credential theft. By shifting decryption to remote servers, attackers avoid detection mechanisms designed to identify on-device activity. At the same time, session cookie theft is increasingly replacing password theft as the primary objective.
The data collected by such tools often marks the beginning of further attacks, including logins from unusual locations, lateral movement within networks, and unauthorised access patterns.
Indicators of compromise include:
Alias: StormStealer
Forum ID: 221756
Registration date: December 12, 2025
Current version: v0.0.2.0 (Gunnar)
Build details: Developed in C++ (MSVC/msbuild), approximately 460 KB in size, targeting Windows systems
This advent of Storm underlines how cybercriminal tools are becoming more advanced, automated, and difficult to detect, requiring organisations to strengthen monitoring of sessions, user behaviour, and access patterns rather than relying solely on traditional credential protection methods.
Threat actors are actively taking advantage of security weaknesses in TBK digital video recorders and outdated TP-Link Wi-Fi routers to install variants of the Mirai botnet on compromised systems. This activity has been documented by researchers at Fortinet FortiGuard Labs and Palo Alto Networks Unit 42.
One of the primary attack vectors involves the exploitation of CVE-2024-3721, a command injection vulnerability with a CVSS score of 6.3, classified as medium severity. This flaw affects TBK DVR-4104 and DVR-4216 devices and is being used to deliver a Mirai-based malware strain identified as Nexcorium.
Security researchers note that IoT devices continue to be heavily targeted because they are widely deployed, frequently lack timely security updates, and are often configured with weak protections. These conditions allow attackers to exploit known vulnerabilities to gain initial access, deploy malicious code, maintain persistence, and ultimately use infected devices to conduct distributed denial-of-service attacks.
This vulnerability has already been observed in previous attack campaigns. Over the past year, it has been used not only to deploy Mirai variants but also a newer botnet known as RondoDox. In addition, earlier reporting highlighted large-scale botnet operations distributing multiple malware families, including Mirai, RondoDox, and Morte, by exploiting weak credentials and outdated vulnerabilities across routers, IoT devices, and enterprise systems.
In the current attack chain described by Fortinet, exploitation of CVE-2024-3721 allows attackers to download a script onto the target device. This script then determines the system’s Linux architecture and retrieves a compatible botnet payload. Once executed, the malware displays a message indicating that the system has been taken over.
Technical analysis shows that Nexcorium follows a structure similar to traditional Mirai variants. It includes encoded configuration tables, a watchdog mechanism to keep the malware active, and dedicated modules for launching DDoS attacks.
The malware also integrates an exploit for CVE-2017-17215, enabling it to target Huawei HG532 devices within the same network. Additionally, it uses a hard-coded list of usernames and passwords to attempt brute-force logins on other systems via Telnet connections.
If these login attempts succeed, the malware gains shell access, establishes persistence using scheduled tasks and system services, and connects to an external command-and-control server. From there, it waits for instructions to launch attacks using protocols such as UDP, TCP, and SMTP. After securing persistence, it deletes the original binary file to reduce the likelihood of detection and analysis.
Researchers describe Nexcorium as representative of modern IoT botnets, combining multiple techniques such as vulnerability exploitation, multi-architecture support, and persistence mechanisms to maintain long-term control over infected devices. Its use of both older vulnerabilities and brute-force tactics highlights its ability to adapt and expand its reach.
Separately, Unit 42 identified automated scanning activity attempting to exploit another vulnerability, CVE-2023-33538, which has a higher CVSS score of 8.8. This flaw affects several end-of-life TP-Link routers, including TL-WR940N (v2 and v4), TL-WR740N (v1 and v2), and TL-WR841N (v8 and v10). While the observed attack attempts were incorrectly executed and did not succeed, the vulnerability itself remains valid.
This vulnerability was added to the Known Exploited Vulnerabilities catalog maintained by the Cybersecurity and Infrastructure Security Agency in June 2025, reflecting its relevance in real-world threat activity. Researchers emphasize that successful exploitation requires authenticated access to the router’s web interface, which can often be achieved if default credentials are still in use.
The attacks linked to this vulnerability are designed to deploy Mirai-like malware containing references to “Condi” within its source code. This malware is capable of updating itself to newer versions and can also operate as a web server, allowing it to spread to additional devices that connect to the infected system.
Because the affected TP-Link routers are no longer supported by the manufacturer, users are advised to replace them with newer devices. Security experts also stress the importance of changing default login credentials, as these remain a major weakness that attackers continue to exploit.
Researchers warn that the continued use of default credentials in IoT environments will remain a persistent security risk. Even vulnerabilities that require authentication can become critical entry points if weak or unchanged credentials are present, enabling attackers to compromise devices and expand botnet networks with relative ease.
An upgraded variant of BX RAT, JanelaRAT, can steal cryptocurrency and financial data from financial organizations, trace mouse inputs, log keystrokes, collect system information, and take screenshots.
In a recent report, Kaspersky said, “One of the key differences between these trojans is that JanelaRAT uses a custom title bar detection mechanism to identify desired websites in victims' browsers and perform malicious actions.” The hackers behind the JanelaRAT attacks constantly modify the malware versions by adding new features.
Telemetry data collected by a Russian cybersecurity firm suggests that around 11,695 attacks happened in Mexico and 14,739 in Brazil in 2025. We do not know how many of these led to a successful exploit.
In June 2023, Zscaler first discovered JanelaRAT in the wild, leveraging ZIP archives containing a VBScript to download another ZIP file, which came with a genuine executable and a DLL payload. The hacker then deploys the DLL side-loading tactic to launch the malware.
An analysis by KPMG in 2025 revealed that the malware is circulated via rogue MSI installer files impersonating as a legit software hosted on trusted sites like GitLab.
"Upon execution, the installer initiates a multi-stage infection process using orchestrating scripts written in Go, PowerShell, and batch,” KPMG said. "These scripts unpack a ZIP archive containing the RAT executable, a malicious Chromium-based browser extension, and supporting components."
The scripts are also made to recognize installed Chromium-based browsers and secretly configure their launch parameters to install the extension. The browser add-on collects system data, cookies, browsing history, tab metadata, and installed extensions. It also triggers actions depending upon URL pattern matches.
The recent malware campaign found by Kaspersky reveals that phishing emails disguised as due invoices are used to lure recipients into downloading a PDF file by opening a link, causing the download of a ZIP archive that starts the attack chain, including DLL side-loading to deploy JanelaRAT.
Since May 2024, JanelaRAT malware has moved from VBScripts to MSI installers, which work as a dropper for the trojan via DLL side-loading and build persistence in the victim system by making a Windows Shortcut (LNK) in the Startup folder that leads to the executable.
According to Kaspersky, “The malware determines if the victim's machine has been inactive for more than 10 minutes by calculating the elapsed time since the last user input.”
If the inactivity is over ten minutes, “the malware notifies the C2 by sending the corresponding message. Upon user activity, it notifies the threat actor again. This makes it possible to track the user's presence and routine to time possible remote operations," Kaspersky said.