Silver Fox, a known threat actor group, has expanded its operations by targeting Indian users through phishing campaigns designed to deploy a remote access trojan known as ValleyRAT, also referred to as Winos 4.0. The campaign relies on region-specific lures tied to income tax notices, indicating a deliberate focus on exploiting local context to increase infection rates.
Phishing emails use income tax urgency to trigger malware execution
The attack chain begins with carefully crafted phishing emails themed around income tax compliance. These messages are designed to create urgency, prompting recipients to open malicious attachments or click embedded links. Once engaged, the payload delivery process is triggered, leading to the download and execution of ValleyRAT on the victim’s system without immediate detection.
DLL hijacking is used to bypass traditional security controls
A core component of the campaign is the use of DLL hijacking to execute malicious code. Silver Fox abuses legitimate applications by replacing or loading malicious dynamic link library files, allowing the malware to run under the guise of trusted software. This technique enables ValleyRAT to evade common security mechanisms, including signature-based antivirus detection.
ValleyRAT’s modular design enables flexible and persistent control
ValleyRAT is built with a modular architecture that allows attackers to dynamically extend its capabilities. Depending on operational needs, modules can be used to enable remote access, exfiltrate data, manipulate files, or execute additional payloads. This flexibility allows Silver Fox to adapt the malware’s behavior over time while maintaining long-term access to compromised environments.
Once installed, ValleyRAT establishes persistence to remain active across system restarts. Observed techniques include embedding malicious components within legitimate system processes and configuring autorun entries. These mechanisms make the malware difficult to remove without thorough forensic analysis and system remediation.
CloudSEK researchers uncovered a multi-layered and stealth-focused kill chain
The campaign was analyzed in detail by CloudSEK researchers Prajwal Awasthi and Koushik Pal, who documented the technical structure of Silver Fox’s operations targeting Indian entities. Their findings highlight a multi-layered kill chain engineered to maximize stealth, reduce detection, and ensure reliable malware deployment and persistence.
The technical breakdown confirms that Silver Fox is investing in region-specific attack strategies rather than broad, opportunistic campaigns. By tailoring lures, delivery mechanisms, and execution techniques, the group increases its success rate while complicating detection efforts for defenders relying on generic threat models.
Defensive readiness is critical as Silver Fox continues to evolve its tactics
As Silver Fox refines its attack techniques and expands its targeting scope, organizations and individual users must reassess their security posture. Maintaining updated threat intelligence, monitoring for DLL hijacking behavior, and strengthening phishing defenses are essential steps in reducing exposure to campaigns of this nature.
