Hackers Weaponizing SVG Files to Stealthily Deliver Malicious Payloads

Cybercriminals have embraced a new deceptive technique that transforms seemingly harmless vector graphics into dangerous malware delivery systems.

A recent campaign targeting Latin America demonstrates how attackers are exploiting oversized SVG files containing embedded malicious payloads to distribute AsyncRAT, a potent remote access trojan capable of comprehensive system compromise.

The campaign begins with carefully crafted phishing emails impersonating legitimate institutions, particularly judicial systems, to create urgency around fictitious legal proceedings or court summons.

Victims receive messages claiming lawsuits or official documents require immediate attention, compelling recipients to open attached SVG files without proper scrutiny.

Unlike traditional malware campaigns that require external command-and-control infrastructure, these weaponized SVG files contain complete malicious packages within themselves.

The technique, known as SVG smuggling, leverages the XML-based nature of Scalable Vector Graphics to embed scripts, interactive elements, and encoded payloads directly into what appears to be an innocent image file.

Welivesecurity analysts noted that these files often exceed 10 MB in size, far larger than typical graphics, and immediately render fake government portals when opened in web browsers.

The attackers appear to utilize artificial intelligence tools to generate customized files for individual targets, with each victim receiving uniquely crafted SVG files stuffed with randomized data to evade signature-based detection systems.

Infection Mechanism and Payload Deployment

The infection process unfolds through a sophisticated multi-stage workflow designed to maintain victim engagement while downloading malicious components.

When users click the SVG attachment, their default web browser renders an elaborate fake portal mimicking Colombia’s judicial system, complete with official logos, government styling, and dynamic progress indicators.

The malicious SVG file contains embedded JavaScript that simulates document verification processes, displaying realistic progress bars and status messages like “Verificando documentos oficiales” and “30% completado” to create authenticity.

During this theatrical display, the script quietly assembles and deploys a password-protected ZIP archive containing the final AsyncRAT payload.

The embedded code includes base64-encoded binary data that gets decoded and assembled on-the-fly:-

const payloadData = "UESDBBQACQgIAGxD+VpRqIWSufYYACn8GAAxAAAAMDFfREVNQU5EQSBQRU5BTCBQT1IgRUwgSlVaR0FETyAwMS...";
const binaryString = atob(payloadData);
const bytes = new Uint8Array(binaryString.length);

The campaign employs DLL sideloading techniques where legitimate applications load malicious libraries, allowing the final AsyncRAT payload to blend with normal system processes and evade detection.

Detection telemetry reveals systematic deployment patterns, with attack spikes occurring mid-week throughout August 2025, primarily targeting Colombian users.

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