XPC Services
Where this stands
A reviewer read the telemetry and concluded there is nothing here to detect that a sibling technique does not already cover.
AN0948 is the only analytic and all three of its log sources are macos:unifiedlog with an empty eventIds array and a 'mitre' string that is a sentence of prose rather than an event selector: 'Unexpected NSXPCConnection calls by non-Apple-signed or abnormal binaries', 'execve: Helper tools invoked through XPC executing unexpected binaries', and 'XPC messages requesting privileged actions from untrusted or unsigned clients'. No brief in this corpus supplies a field schema for macos/unifiedlog, and no rule in the corpus uses product: macos for that reason — the published T1558.005 rule states the same conclusion for its own macOS arm. Any selection written here would have to invent field names, which hard rule 2 forbids precisely because such a rule parses, renders in four backends and matches nothing. The blocker is not only the missing Sigma vocabulary. […]
What the technique is
Adversaries can provide malicious content to an XPC service daemon for local code execution. macOS uses XPC services for basic inter-process communication between various processes, such as between the XPC Service daemon and third-party application privileged helper tools. Applications can send messages to the XPC Service daemon, which runs as root, using the low-level XPC Service C API or the high level NSXPCConnection API in order to handle tasks that require elevated privileges (such as network connections). Applications are responsible for providing the protocol definition which serves as a blueprint of the XPC services. Developers typically use XPC Services to provide applications stability and privilege separation between the application client and the daemon. Adversaries can abuse XPC services to execute malicious content. Requests for malicious execution can be passed through the application's XPC Services handler. This may also include identifying and abusing improper XPC client validation and/or poor sanitization of input parameters to conduct Exploitation for Privilege Escalation.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN0948
Detects anomalous use of macOS XPC services for code execution. Monitors for processes invoking privileged XPC daemons with abnormal parameters, unexpected binaries communicating over NSXPCConnection, or helper tools executing code outside of their expected parent process lineage. Correlates process access attempts to system-level daemons, privilege escalations via XPC misconfigurations, and injection of malicious payloads through inter-process communication.
Technique names and descriptions © MITRE ATT&CK®, CC BY 4.0. Not endorsed by MITRE.