Hackers Exploit SVG Files with Embedded JavaScript to Deploy Malware on Windows Systems

Threat actors are increasingly using Scalable Vector Graphics (SVG) files to get beyond traditional defenses in the quickly developing field of cybersecurity.

Unlike raster formats such as JPEG or PNG, which store pixel-based data, SVGs are XML-structured documents that define vector shapes, paths, and text, enabling seamless scalability.

This inherent flexibility, however, permits the embedding of executable JavaScript code, which can activate upon rendering in a web browser a default behavior on many Windows systems.

According to Seqrite report, attackers exploit this by distributing malicious SVGs through spear-phishing emails or cloud storage platforms like Dropbox, Google Drive, or OneDrive, often evading email security gateways due to their innocuous appearance.

SVG as a Vector for Phishing

The attack chain typically initiates with a deceptive email attachment, such as one disguised as “Upcoming Meeting.svg” or “Your-to-do-List.svg,” accompanied by compelling subject lines like “Reminder for your Scheduled Event 7212025.msg.”

Upon opening, the SVG file loads in the browser, executing embedded scripts that decode obfuscated payloads and redirect victims to command-and-control (C2) phishing domains, potentially leading to credential theft or malware deployment.

The technical sophistication of these attacks lies in the SVG’s ability to conceal malicious logic within its XML framework.

For instance, adversaries embed

A decoded payload might then utilize constructs like window.location = ‘javascript:’ + decoded_string; to force browser redirection to sites such as hxxps://hju[.]yxfbynit[.]es/koRfAEHVFeQZ!bM9.

These destinations often feature Cloudflare CAPTCHA gates to filter automated scanners, followed by hyper-realistic phishing pages mimicking services like Microsoft 365 or Google Workspace.

Here, attackers capture credentials in real-time, validating them against legitimate APIs to ensure authenticity before exfiltrating data.

In advanced variants, the redirected page could serve as a dropper for secondary malware, exploiting browser vulnerabilities or social engineering to install persistent threats like keyloggers or ransomware.

This method’s efficacy stems from SVGs bypassing many antivirus solutions, which prioritize executable binaries over vector graphics, and the automatic browser handling on Windows, where no dedicated viewer is typically configured.

Defensive Strategies

To mitigate these risks, organizations must adopt layered defenses incorporating deep content inspection tools capable of parsing XML and JavaScript within SVGs.

Disabling automatic browser rendering for untrusted files, through group policies or endpoint configurations, can prevent unintended script execution.

Employee training programs should emphasize vigilance against unfamiliar attachments, highlighting indicators like mismatched sender domains or generic file names.

Network monitoring for anomalous redirects, unusual script behaviors, and traffic to known phishing C2s further bolsters resilience.

As cybercriminals refine these techniques, integrating threat intelligence feeds and behavioral analytics into security operations centers becomes essential.

By treating SVGs not merely as images but as potential code execution vectors, enterprises can proactively address this evolving threat landscape, reducing the likelihood of successful breaches.

Indicators of Compromise (IOCs)

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