Ghost Push: Background Delivery via Expired APNs Tokens

Overview

This repository documents a vulnerability observed in iOS 18.6.2, where expired or unavailable Apple Push Notification service (APNs) tokens are still reused by system daemons to deliver silent push messages — even without an active app context or token re-registration.

This violates the expected APNs token lifecycle and enables unauthorized background processing. It introduces risks such as covert communication, post-removal message delivery, and potential data leakage.

Affected Platform

Operating System: iOS 18.6.2 (Production)
Components: apsd, cloudd, identityservicesd, StatusKitAgent
Context: Observed in a real-world, non-laboratory production environment

Technical Summary

The system repeatedly invoked copyTokenForDomain to retrieve a push token, but received null responses.
No evidence of registerForPush, registerTopic, or re-registration events.
Despite this, apsd retrieved a previously cached token and delivered a push message.
System daemons processed the push, even though:
- The corresponding app was not active
- The app had not freshly registered for push notifications
This behavior bypasses lifecycle validation checks and introduces a persistent, unauthorized communication path.

Timeline (Sample Logs)

18:07:50.236249 apsd: copyTokenForDomain push.apple.com (null)
18:07:54.012876 apsd: copyTokenForDomain push.apple.com <private>, PerAppToken.v0
18:07:54.119270 apsd: found cached token for topic: com.apple.icloud-container.com.apple.willowd
18:07:57.025320 cloudd: TCC approved access for container com.apple.homekit.config

Log Evidence: https://ia601600.us.archive.org/28/items/ghost-push/Ghost%20Push.mov

Impact

Violation of expected APNs token lifecycle enforcement
Silent push delivery without user interaction or app activity
Persistence of push capability even after app removal
Potential for covert communication, data exfiltration, or command-and-control (C2) channels via system daemons

Recommendations

Apple should consider the following mitigations:

Invalidate cached tokens when copyTokenForDomain returns null
Enforce rejection of push messages that lack a recently registered token
Prevent background system daemons from processing pushes associated with unregistered or removed applications
Audit APNs routing logic to ensure real-time token validation and eliminate reliance on stale cached data

Suggested CVSS

Vector: AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Base Score: 7.5 (High)

References

Apple Push Notification Service (APNs) Documentation
Affected system daemons: apsd, cloudd, identityservicesd, StatusKitAgent

Disclaimer

This repository is provided for educational and defensive security research purposes only.