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T1037.004 RC Scripts

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 can establish persistence by adding a malicious binary path or shell commands to rc.local, rc.common, and other RC scripts specific to the Unix-like distribution.12 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 IoT or embedded systems.3

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. 45 This technique can be used on Mac OS X Panther v10.3 and earlier versions which still execute the RC scripts.6 To maintain backwards compatibility some systems, such as Ubuntu, will execute the RC scripts if they exist with the correct file permissions.7

Item Value
ID T1037.004
Sub-techniques T1037.001, T1037.002, T1037.003, T1037.004, T1037.005
Tactics TA0003, TA0004
Platforms Linux, macOS
Permissions required root
Version 2.0
Created 15 January 2020
Last Modified 27 April 2021

Procedure Examples

ID Name Description
S0687 Cyclops Blink Cyclops Blink has the ability to execute on device startup, using a modified RC script named S51armled.9
S0690 Green Lambert Green Lambert can add init.d and rc.d files in the /etc folder to establish persistence.1011
S0394 HiddenWasp HiddenWasp installs reboot persistence by adding itself to /etc/rc.local.2
S0278 iKitten iKitten adds an entry to the rc.common file for persistence.8

Mitigations

ID Mitigation Description
M1022 Restrict File and Directory Permissions Limit privileges of user accounts so only authorized users can edit the rc.common file.

Detection

ID Data Source Data Component
DS0017 Command Command Execution
DS0022 File File Creation
DS0009 Process Process Creation

References

  1. Iran Threats . (2017, December 5). Flying Kitten to Rocket Kitten, A Case of Ambiguity and Shared Code. Retrieved May 28, 2020. ↩

  2. Sanmillan, I. (2019, May 29). HiddenWasp Malware Stings Targeted Linux Systems. Retrieved June 24, 2019. ↩↩

  3. Paul Litvak. (2020, May 4). Kaiji: New Chinese Linux malware turning to Golang. Retrieved December 17, 2020. ↩

  4. Apple. (2016, September 13). Daemons and Services Programming Guide - Creating Launch Daemons and Agents. Retrieved February 24, 2021. ↩

  5. Apple. (2016, September 13). Startup Items. Retrieved July 11, 2017. ↩

  6. Patrick Wardle. (2014, September). Methods of Malware Persistence on Mac OS X. Retrieved July 5, 2017. ↩

  7. Canonical Ltd.. (n.d.). systemd-rc-local-generator - Compatibility generator for starting /etc/rc.local and /usr/sbin/halt.local during boot and shutdown. Retrieved February 23, 2021. ↩

  8. Patrick Wardle. (n.d.). Mac Malware of 2017. Retrieved September 21, 2018. ↩

  9. Sandvik, Runa. (2021, October 1). Made In America: Green Lambert for OS X. Retrieved March 21, 2022. ↩

  10. Sandvik, Runa. (2021, October 18). Green Lambert and ATT&CK. Retrieved March 21, 2022. ↩