Could Your Browser Be Vulnerable to Chihuahua Stealer?

Article Highlights
Off On

In 2025, cybersecurity experts are alarmed by a newly detected strain of info stealer called the Chihuahua Stealer. This malware uses advanced techniques that put browser data and cryptocurrency wallet extensions at risk. First flagged by a Reddit user in April of this year, it has since been subjected to detailed analysis, revealing a multitude of sophisticated methods aimed at bypassing conventional security measures. Despite its name, the Chihuahua Stealer employs an unexpectedly advanced arsenal like stealthy loading, scheduled task persistence, and multi-staged payloads designed to make detection exceptionally difficult. Its emergence highlights an escalating challenge in cybersecurity—how to effectively shield consumers and organizations from increasingly complex malware threats. For individuals and companies alike, understanding how this malware operates and what defenses can be implemented is crucial.

Multi-Stage PowerShell Script Infection

The initial form of attack used by the Chihuahua Stealer involves an intricately designed multi-stage PowerShell script, showcasing its complexity and ability to maintain persistence quietly. A major insight from the investigation conducted by G Data CyberDefense found that the malware begins its attack with an obfuscated PowerShell script that users may unknowingly execute, believing it’s a legitimate document. Once activated, the loader triggers a complex multi-staged execution chain employing Base64 encoding and hex-string obfuscation while utilizing scheduled jobs to ensure continued presence. The initial steps involve a lightweight launcher that stealthily executes a Base64-encoded PowerShell string using “iex,” effectively circumventing execution policies. This approach conceals the payload from static analysis and signature-based detection. Then, it progresses to decode and reconstruct a hex payload, dynamically assembling to avoid detection by static and sandbox analyses. The persistence mechanism involves scheduling tasks that scan for infection markers, signaled by “*.normaldaki” files. When markers are detected, subsequent steps involve retrieving additional payloads from command-and-control servers, directed by specific commands. This process culminates in the introduction of a .NET assembly obtained from a remote domain, loading a Base64-obfuscated payload from platforms like OneDrive directly into memory via reflection. This method enables execution while meticulously erasing traces, such as console outputs and clipboard data, minimizing observable indicators of the malware’s presence. Through these intricate mechanisms, the Chihuahua Stealer sets a precedent for modular, adaptive malware capable of persistent data gathering despite efforts to counteract its effects. The complexity and concealment of these operations enable the Chihuahua Stealer to traverse systems quietly, posing a formidable security threat.

Execution, Encryption, and Data Exfiltration

Upon completion of its initial entry, the Chihuahua Stealer initiates its main functions, engaging in a process designed for efficient data extraction and secure exfiltration. A signature step involves executing the DedMaxim() function, during which it displays transliterated Russian rap lyrics on-screen—a signature likely used for identification purposes rather than functionality. However, the subsequent PopilLina() function holds the key operational elements, where the malware interacts with Windows Management Instrumentation (WMI) processes to gather identifying details such as the machine name and disk serial number, which are then obfuscated and hashed to create a unique identifier for the compromised system. This identifier becomes instrumental for naming archives and directories intended to store exfiltrated data. The malware meticulously scans user directories for browser-related files and crypto wallet extension data, employing dynamic path analysis for browsers installed on the user’s system.

Methods for extracting valuable credentials extend to cookies, autofill data, browsing history, sessions, and payment information across detected browsers, as well as targeting crypto wallet extensions by copying pertinent data from folders associated with known wallet extension IDs. After gathering these sensitive data points, the malware processes them for encryption and eventual exfiltration, creating a plaintext file named Brutan.txt for visibility within the working directory. These data are then compressed into a “.chihuahua” archive before encrypting the compiled archive using AES-GCM protocols. The resulting encrypted data file, termed “.VZ”, is subjected to exfiltration attempts toward external servers in a retry-loop format, exploiting headers to mimic a binary file upload. This activity transforms the malware’s presence from local to network-based, posing threats beyond immediate infection scope. Ultimately, data exfiltration operations culminate in the VseLegalno() function, harnessing a WebClient instance to upload the encrypted file to specified external servers, thereby targeting an extended range of vulnerabilities.

Mitigation Recommendations

The Chihuahua Stealer kicks off its attack using a cleverly crafted multi-stage PowerShell script, designed for stealth and persistence. Insights from G Data CyberDefense reveal the malware initiates with an obfuscated PowerShell script that tricks users into executing it, mistaking it for a genuine document. Once running, it triggers a complex execution chain using Base64 encoding and hex-string obfuscation while leveraging scheduled jobs for endurance. The attack starts with a lightweight launcher stealthily running a Base64-encoded PowerShell command through “iex,” sidestepping execution policies. This tactic hides the payload from static analysis and signature detection, decoding a hex payload dynamically to thwart static and sandbox analysis. Persistence involves scheduled tasks that detect infection markers, identified by “*.normaldaki” files. Upon spotting these, further payloads are fetched from command-and-control servers following specific instructions. The climax involves a .NET assembly from a remote domain, loading a Base64-obfuscated payload directly into memory, erasing traces and minimizing the malware’s visible presence. Despite countermeasures, the Chihuahua Stealer remains an adaptable, persistent threat.

Explore more

Can AI Redefine C-Suite Leadership with Digital Avatars?

I’m thrilled to sit down with Ling-Yi Tsai, a renowned HRTech expert with decades of experience in leveraging technology to drive organizational change. Ling-Yi specializes in HR analytics and the integration of cutting-edge tools across recruitment, onboarding, and talent management. Today, we’re diving into a groundbreaking development in the AI space: the creation of an AI avatar of a CEO,

Cash App Pools Feature – Review

Imagine planning a group vacation with friends, only to face the hassle of tracking who paid for what, chasing down contributions, and dealing with multiple payment apps. This common frustration in managing shared expenses highlights a growing need for seamless, inclusive financial tools in today’s digital landscape. Cash App, a prominent player in the peer-to-peer payment space, has introduced its

Scowtt AI Customer Acquisition – Review

In an era where businesses grapple with the challenge of turning vast amounts of data into actionable revenue, the role of AI in customer acquisition has never been more critical. Imagine a platform that not only deciphers complex first-party data but also transforms it into predictable conversions with minimal human intervention. Scowtt, an AI-native customer acquisition tool, emerges as a

Hightouch Secures Funding to Revolutionize AI Marketing

Imagine a world where every marketing campaign speaks directly to an individual customer, adapting in real time to their preferences, behaviors, and needs, with outcomes so precise that engagement rates soar beyond traditional benchmarks. This is no longer a distant dream but a tangible reality being shaped by advancements in AI-driven marketing technology. Hightouch, a trailblazer in data and AI

How Does Collibra’s Acquisition Boost Data Governance?

In an era where data underpins every strategic decision, enterprises grapple with a staggering reality: nearly 90% of their data remains unstructured, locked away as untapped potential in emails, videos, and documents, often dubbed “dark data.” This vast reservoir holds critical insights that could redefine competitive edges, yet its complexity has long hindered effective governance, making Collibra’s recent acquisition of