Weaponized SVG Files Used by Threat Actors to Redirect Users to Malicious Sites

Cybercriminals are increasingly weaponizing Scalable Vector Graphics (SVG) files to orchestrate sophisticated phishing campaigns.

According to research from Intezer, a cybersecurity firm that triages millions of alerts for enterprises globally, attackers are embedding malicious JavaScript within SVG files to redirect unsuspecting users to credential-harvesting phishing sites.

This technique, dubbed “Script in the Shadows,” has proven alarmingly effective, bypassing modern email security filters and endpoint protections to reach victims’ inboxes undetected.

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The abuse of SVG, an XML-based format for rendering two-dimensional graphics, leverages its inherent ability to house scripts and interactive elements, turning a seemingly innocuous image file into a potent attack vector.

SVG Files — **MHT Files Nesting in OpenXML Documents**

Decoding the Stealthy Attack Mechanism

The intricacy of this phishing method lies in its multi-layered obfuscation, designed to evade static analysis by security scanners.

Intezer’s analysis revealed that threat actors encode malicious JavaScript in Base64 within SVG files, often concealed inside or tags.

Once decoded, the script unveils a heavily obfuscated payload employing techniques such as string reversal, junk character insertion, and hexadecimal-to-ASCII conversion.

These steps complicate detection by disrupting pattern-matching algorithms and regular expression-based scanners.

The final stage reconstructs a malicious URL, redirecting the victim to a phishing page via window.location.href.

According to the Report, A striking finding from Intezer’s research was that VirusTotal initially flagged one such SVG file (IOC: b5a7406d5b4ef47a62b8dd1e4bec7f1812162433955e3a5b750cc471cbfad93e) as trusted with zero detections, underscoring a critical blind spot in conventional security tools.

This evasion highlights why SVG files, widely used for legitimate purposes, are rarely subjected to deep inspection for embedded scripts, making them an ideal vehicle for covert attacks.

Intezer’s research team developed a custom tool to dissect this technique, confirming that the Base64-encoded JavaScript within the SVG file was meticulously crafted to avoid static detection.

The broader implication is a growing need for advanced, format-aware inspection mechanisms in cybersecurity defenses.

Traditional signature-based or surface-level scanning fails to address the structural obfuscation employed here, where malicious intent only surfaces upon decoding or execution.

As phishing actors exploit the trust and flexibility of unconventional file formats like SVG, organizations must prioritize dynamic analysis and deeper content parsing to counter such threats.

Intezer warns that this is not a theoretical exploit but a real-world tactic actively bypassing email gateways, urging the security community to adapt swiftly to these evolving deception strategies.

The persistence of phishing, fueled by human psychology and technical innovation, demands a proactive stance combining research collaboration, enhanced tooling, and awareness to stay ahead of adversaries who operate in the shadows of trusted technologies.