SVG Smuggling

What the technique is

Adversaries may smuggle data and files past content filters by hiding malicious payloads inside of seemingly benign SVG files. SVGs, or Scalable Vector Graphics, are vector-based image files constructed using XML. As such, they can legitimately include tags that enable adversaries to include malicious JavaScript payloads. However, SVGs may appear less suspicious to users than other types of executable files, as they are often treated as image files. SVG smuggling can take a number of forms. For example, threat actors may include content that: Assembles malicious payloads Downloads malicious payloads Redirects users to malicious websites Displays interactive content to users, such as fake login forms and download buttons. SVG Smuggling may be used in conjunction with HTML Smuggling where an SVG with a malicious payload is included inside an HTML file. SVGs may also be included in other types of documents, such as PDFs.

What MITRE says you would watch

• AN1407

  Detects suspicious SVG file creation or download events followed by script engine execution (e.g., wscript.exe, mshta.exe, rundll32.exe), network callbacks, or browser-based credential collection.

• AN1408

  Detects downloaded SVG files followed by execution of browser processes or tools like xdg-open, and rapid follow-on network connections or process spawns to interpreters like python or bash.

• AN1409

  Detects SVGs downloaded via browser that invoke AppleScript, osascript, or JavaScriptCore processes, followed by network egress or file drop to LaunchAgents or ~/Library.