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RC Scripts (T1037.004) is a MITRE ATT&CK technique associated with Persistence, Privilege Escalation . Adversaries may establish persistence by modifying RC scripts, which are executed during a Unix like system’s startup.
RC Scripts (T1037.004) is a MITRE ATT&CK technique associated with Persistence, Privilege Escalation. Adversaries may establish persistence by modifying RC scripts, which are executed during a Unix-like system’s startup.
Attackers use RC Scripts because it provides a reliable way to advance their objective within the Persistence, Privilege Escalation tactic, often with a favorable balance of impact versus detectability on macOS, Linux, Network Devices, ESXi environments. Defenders should assess this behavior in the context of the affected platform and adjacent activity rather than treating it as a standalone indicator.
Adversaries may establish persistence by modifying RC scripts, which are executed during a Unix-like system’s startup. These files allow system administrators to map and start custom services at startup for different run levels. RC scripts require root privileges to modify.
Adversaries may establish persistence by adding a malicious binary path or shell commands to <code>rc.local</code>, <code>rc.common</code>, and other RC scripts specific to the Unix-like distribution.(Citation: IranThreats Kittens Dec 2017)(Citation: Intezer HiddenWasp Map 2019) Upon reboot, the system executes the script's contents as root, resulting in persistence.
Adversary abuse of RC scripts is especially effective for lightweight Unix-like distributions using the root user as default, such as ESXi hypervisors, IoT, or embedded systems.(Citation: intezer-kaiji-malware) As ESXi servers store most system files in memory and therefore discard changes on shutdown, leveraging /etc/rc.local.d/local.sh is one of the few mechanisms for enabling persistence across reboots.(Citation: Juniper Networks ESXi Backdoor 2022)
Several Unix-like systems have moved to Systemd and deprecated the use of RC scripts. This is now a deprecated mechanism in macOS in favor of Launchd.(Citation: Apple Developer Doco Archive Launchd)(Citation: Startup Items) This technique can be used on Mac OS X Panther v10.3 and earlier versions which still execute the RC scripts.(Citation: Methods of Mac Malware Persistence) To maintain backwards compatibility some systems, such as Ubuntu, will execute the RC scripts if they exist with the correct file permissions.(Citation: Ubuntu Manpage systemd rc)
No universal command represents RC Scripts. Capture the exact command line, arguments, parent process, account, host, and execution time from the investigated environment; do not operationalize unverified examples.
| Event ID | Log Channel | What It Indicates |
|---|---|---|
| Not universally applicable | Validate platform coverage | This technique may not produce a Windows event; use telemetry native to the affected platform. |
| Sysmon Event ID | Name | Why It's Relevant Here |
|---|---|---|
| Environment-specific | Validate configured telemetry | Use process, network, file, registry, DNS, or image-load telemetry only when relevant and enabled. |
No MITRE detection guidance published for this technique.
Relevant ATT&CK Data Sources: N/A
A universal Sigma rule would create unreliable results because this technique has no single guaranteed observable. Build detection logic from a documented behavior and supported data source, scope it to the affected platform, and validate it against benign administrative activity before deployment.
Start with the data sources named in the detection section. Scope searches by asset, identity, and time window; correlate the primary behavior with preceding access and subsequent actions. A portable query is intentionally not provided where the technique lacks a universal schema or observable.