Description

An insecure PIN derivation mechanism in ABR allows a low-privileged user to escalate privileges to administrator by communicating over Cross-Process Communication (XPC) while masquerading as an Apple-signed process.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-08-26T08:16:46.600Z",
  "pubdate": "2026-08-26T08:16:46.600Z",
  "executiveSummary": "This vulnerability exists in the ABR PIN derivation mechanism, which fails to properly authenticate the source of requests transmitted over Cross-Process Communication (XPC). By failing to verify the identity and signing status of the calling process, the mechanism allows low-privileged users to bypass standard security controls.\nAn attacker can exploit this flaw by masquerading as a trusted, Apple-signed process to interact with the ABR service. Successful exploitation enables unauthorized access to administrative functions, resulting in a local privilege escalation. The vulnerability poses a significant security risk, as it allows non-administrative entities to execute privileged operations, potentially leading to a complete compromise of the affected service's security posture and the underlying system integrity.\nExploitation requires local access to the system and the ability to interact with the XPC interface. No special network exposure is required, as the vector is strictly local to the Inter-Process Communication (IPC) boundary.",
  "technicalDetails": "The vulnerability originates from a flawed implementation of the XPC communication protocol within the ABR service. Specifically, the service performs PIN derivation based on incoming messages without performing cryptographically robust verification of the peer process’s identity (the PID or Audit Token).\nThe ABR service relies on implicit trust when receiving XPC messages. The mechanism assumes that messages arriving over the established connection originate from legitimate, authorized components. However, the service does not enforce code-signing requirements on the calling process. An attacker can instantiate a malicious process and leverage XPC mechanisms to inject requests into the ABR service. By spoofing the entitlement or signature status typically associated with Apple-signed processes, the attacker can cause the ABR service to treat the unauthorized request as a legitimate administrative command.\nThe attack flow proceeds as follows: First, the attacker identifies the XPC service interface exposed by ABR. Second, the attacker crafts a malicious payload designed to initiate the PIN derivation routine. Third, the attacker initiates a connection to the ABR XPC listener. During the handshake or request phase, the attacker mimics the environment of an Apple-signed process. Because the ABR component fails to perform a 'check-entitlements' or 'sec-code-check' routine on the incoming connection, the service incorrectly validates the attacker's request.\nOnce the service accepts the fraudulent request, the PIN derivation logic is triggered under the context of the ABR process, which runs with administrative privileges. This effectively allows the attacker to manipulate sensitive data, bypass PIN requirements, or transition the process to an unauthorized state. Post-exploitation, the attacker gains the ability to execute operations restricted to the administrator, effectively escalating their local privileges to match those of the ABR service daemon. This failure to implement proper access control checks during IPC/XPC communication creates a critical bypass of the system's intended security architecture."
}