Detect SVG Smuggling in Elastic Security
Adversaries may smuggle data and files past content filters by hiding malicious payloads inside of seemingly benign SVG files. SVGs are vector-based image files constructed using XML and can legitimately include <script> tags, enabling adversaries to embed malicious JavaScript payloads. SVGs may appear less suspicious to users than other executable file types since they are often treated as image files. SVG smuggling can assemble or download malicious payloads, redirect users to malicious websites, or display interactive content such as fake login forms. SVG Smuggling may be used in conjunction with HTML Smuggling where an SVG with a malicious payload is included inside an HTML file.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1027 Obfuscated Files or Information
- Sub-technique
- T1027.017 SVG Smuggling
- Canonical reference
- https://attack.mitre.org/techniques/T1027/017/
Elastic Detection Query
any where
(event.category == "process" and event.type == "start" and
process.parent.name : ("chrome.exe", "msedge.exe", "firefox.exe", "iexplore.exe", "opera.exe", "brave.exe", "outlook.exe", "thunderbird.exe", "winmail.exe") and
process.name : ("cmd.exe", "powershell.exe", "pwsh.exe", "wscript.exe", "cscript.exe", "mshta.exe", "rundll32.exe", "regsvr32.exe", "certutil.exe", "msiexec.exe", "bitsadmin.exe", "curl.exe", "wget.exe"))
or
(event.category == "file" and event.type == "creation" and
file.extension : "svg" and
process.name : ("chrome.exe", "msedge.exe", "firefox.exe", "iexplore.exe", "opera.exe", "brave.exe", "outlook.exe", "thunderbird.exe", "winmail.exe"))
or
(event.category == "process" and event.type == "start" and
process.parent.name : ("chrome.exe", "msedge.exe", "firefox.exe", "iexplore.exe", "opera.exe", "brave.exe", "outlook.exe", "thunderbird.exe", "winmail.exe") and
process.name : ("cmd.exe", "powershell.exe", "pwsh.exe", "wscript.exe", "cscript.exe", "mshta.exe", "rundll32.exe", "regsvr32.exe", "certutil.exe", "msiexec.exe", "bitsadmin.exe", "curl.exe", "wget.exe") and
(process.command_line like~ "*downloads*" or process.command_line like~ "*\\temp\\*" or process.command_line like~ "*appdata*"))Detects SVG Smuggling (T1027.017) using Elastic EQL's 'any where' construct to cover three behavioral patterns across multiple event categories in a single rule: (1) a browser or mail client process directly spawning a suspicious child interpreter or LOLBin; (2) an SVG file being written to disk by a browser or mail client, indicating a payload drop; and (3) a browser/mail-parented suspicious process executing with command-line context referencing common drop paths (Downloads, Temp, AppData). Uses ECS field names compatible with Elastic Endpoint Security and Winlogbeat/Filebeat with Sysmon.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate browser extensions or download managers (e.g., IDM, Free Download Manager) that invoke cmd.exe or powershell.exe as post-download handlers — these will match the parent-child process pattern without any malicious SVG involvement.
- Enterprise software deployment portals accessed via browser where clicking an installer link causes the browser to spawn msiexec.exe or a similar LOLBin — common in large organisations using web-based software catalogues.
- Electron-based applications (VS Code, Slack, Teams) that embed a Chromium renderer (process.parent.name matching browser patterns) and legitimately invoke PowerShell or cmd.exe for shell integration, terminal features, or auto-update workflows.
- Web-based SVG design tools (Figma native desktop with embedded browser, or browser-based Inkscape/Canva equivalents) that write SVG files to disk and then invoke local script interpreters for export or processing pipelines.
Other platforms for T1027.017
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Create and Open Malicious SVG with Embedded JavaScript
Expected signal: Sysmon Event ID 11: File Create — TargetFilename ending in Invoice-2024.svg written to Downloads directory by powershell.exe. Sysmon Event ID 1: Process Create — browser process (e.g., msedge.exe or chrome.exe) launched with the SVG file path as argument. Sysmon Event ID 3: Network Connection — may be generated if browser makes requests after opening file.
- Test 2SVG Smuggling with Blob URL Payload Download Simulation
Expected signal: Sysmon Event ID 11: File Create — document-viewer.svg written to Downloads by powershell.exe. If opened in browser: Sysmon Event ID 11 — browser may write document.exe to Downloads directory. Sysmon Event ID 1 — browser process launch with SVG path. Network telemetry: Blob URL creation stays local (no external network), but browser history records the file:// URI.
- Test 3SVG File Delivered via Email Simulation with Zone Identifier Check
Expected signal: Sysmon Event ID 11: File Create — Invoice_March2024.svg created in Outlook INetCache directory by powershell.exe. Sysmon Event ID 15 (FileCreateStreamHash): ADS Zone.Identifier written to the SVG file, indicating internet-sourced content (Zone=3). This ADS event is a strong indicator of an externally-sourced file.
- Test 4SVG Embedded in HTML File (HTML Smuggling Combination)
Expected signal: Sysmon Event ID 11: File Create — invoice-document.html written to Downloads by powershell.exe. Select-String output confirms presence of <svg>, <script>, atob, and blob indicators in the file. If opened in browser: potential Sysmon Event ID 11 for invoice.exe creation in Downloads.
References (10)
- https://attack.mitre.org/techniques/T1027/017/
- https://blog.talosintelligence.com/html-smugglers-turn-to-svg-images/
- https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/pixel-perfect-trap-the-surge-of-svg-borne-phishing-attacks/
- https://www.bleepingcomputer.com/news/security/phishing-emails-increasingly-use-svg-attachments-to-evade-detection/
- https://cofense.com/blog/svg-files-abused-in-emerging-campaigns/
- https://learn.microsoft.com/en-us/microsoft-365/security/defender-endpoint/advanced-hunting-devicefileevents-table
- https://learn.microsoft.com/en-us/microsoft-365/security/defender-endpoint/advanced-hunting-deviceprocessevents-table
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1027.006/T1027.006.md
- https://www.w3.org/TR/SVG2/interact.html#EventAttributes
- https://docs.splunk.com/Documentation/SplunkCloud/latest/SearchReference/CommonStatsFunctions
Unlock Pro Content
Get the full detection package for T1027.017 including response playbook, investigation guide, and atomic red team tests.