DEFCON: New Red Team Tactic

Evil Fonts deceive a viewer by rendering a different letter than is actually on the disk. Evil Fonts can poison HTML, DOCX, PDFs, and anywhere else you can bring your own fonts. Works great in Windows corporate networks for bypassing security tooling, initial access through JavaScript free click fix (beats mitm web security tooling), and leaving traps around the network to harvest shells.

Imagine thinking you are copying whoami but what is actually on the disk is rm -rf \~

Demos:

(Use desktop)

https://doctoreww.github.io/EvilFontTool/

For the demos, copy and paste the HTML/DOCX to a notepad to remove the evil fonts. For the AI ones imagine your security tooling inspects the benign text on disk, but shows the obviously malicious extortion to the user.

Labs:

https://github.com/DoctorEww/EvilFontTool/blob/main/labs%2FREADME.md

Lab Walkthrough:

https://github.com/DoctorEww/EvilFontTool/blob/main/labs%2Fwalkthrough.md

Some evil font uses:

Tamper homework to make it so students poison AI queries

Poison help desk documentation

Bypass email filters

Clickfix

Beat resume AI filters

Impact

This technique can be used to bypass security tooling that relies on inspecting machine-readable text, enabling attackers to deliver malicious commands or content that appear benign. It facilitates initial access in corporate networks, evades AI content filters, and allows attackers to plant traps or poison documentation. The deception can lead to execution of unintended commands by users copying and pasting text, potentially causing data loss or system compromise. However, no active exploits in the wild are reported at this time.

Defensive guidance

No official patches or vendor advisories are available as this is a novel red team tactic rather than a software vulnerability. Mitigation involves awareness and detection strategies such as verifying text integrity by copying content into plain text editors to reveal discrepancies, disabling or restricting custom font usage in sensitive environments, and enhancing security tools to detect font-based text manipulation. Organizations should educate users about the risks of copying and pasting commands from untrusted documents and consider implementing controls on document handling and font usage.

Summary

EvilFontTool leverages 'evil fonts' that remap glyphs so that the visible text differs from the underlying text data. This discrepancy enables attackers to craft documents that appear safe or benign to human viewers and security tools that inspect text on disk, while actually containing malicious commands or content. The tool supports multiple formats including HTML, DOCX, and PDF, and can be used for pastejacking without JavaScript, AI filter evasion, and document poisoning. The technique is demonstrated with examples such as tampering homework, poisoning help desk documents, and bypassing AI resume filters. The underlying method exploits font rendering to deceive both users and automated security systems.

DEFCON: New Red Team Tactic

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AI analysisMachine-generated, updated 9 Aug 2026, 04:26 UTC

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