Boot or Logon Initialization Scripts: Скрипты RC
Other sub-techniques of Boot or Logon Initialization Scripts (5)
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 rc.local, rc.common, 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)
Примеры процедур |
|
| Название | Описание |
|---|---|
| Velvet Ant |
Velvet Ant used a modified `/etc/rc.local` file on compromised F5 BIG-IP devices to maintain persistence.(Citation: Sygnia VelvetAnt 2024A) |
| HiddenWasp |
HiddenWasp installs reboot persistence by adding itself to |
| APT29 |
APT29 has installed a run command on a compromised system to enable malware execution on system startup.(Citation: Mandiant APT29 Eye Spy Email Nov 22) |
| Green Lambert |
Green Lambert can add |
| Cyclops Blink |
Cyclops Blink has the ability to execute on device startup, using a modified RC script named S51armled.(Citation: NCSC Cyclops Blink February 2022) |
| iKitten |
iKitten adds an entry to the rc.common file for persistence.(Citation: objsee mac malware 2017) |
Контрмеры |
|
| Контрмера | Описание |
|---|---|
| Restrict File and Directory Permissions |
Restricting file and directory permissions involves setting access controls at the file system level to limit which users, groups, or processes can read, write, or execute files. By configuring permissions appropriately, organizations can reduce the attack surface for adversaries seeking to access sensitive data, plant malicious code, or tamper with system files. Enforce Least Privilege Permissions: - Remove unnecessary write permissions on sensitive files and directories. - Use file ownership and groups to control access for specific roles. Example (Windows): Right-click the shared folder → Properties → Security tab → Adjust permissions for NTFS ACLs. Harden File Shares: - Disable anonymous access to shared folders. - Enforce NTFS permissions for shared folders on Windows. Example: Set permissions to restrict write access to critical files, such as system executables (e.g., `/bin` or `/sbin` on Linux). Use tools like `chown` and `chmod` to assign file ownership and limit access. On Linux, apply: `chmod 750 /etc/sensitive.conf` `chown root:admin /etc/sensitive.conf` File Integrity Monitoring (FIM): - Use tools like Tripwire, Wazuh, or OSSEC to monitor changes to critical file permissions. Audit File System Access: - Enable auditing to track permission changes or unauthorized access attempts. - Use auditd (Linux) or Event Viewer (Windows) to log activities. Restrict Startup Directories: - Configure permissions to prevent unauthorized writes to directories like `C:\ProgramData\Microsoft\Windows\Start Menu`. Example: Restrict write access to critical directories like `/etc/`, `/usr/local/`, and Windows directories such as `C:\Windows\System32`. - On Windows, use icacls to modify permissions: `icacls "C:\Windows\System32" /inheritance:r /grant:r SYSTEM:(OI)(CI)F` - On Linux, monitor permissions using tools like `lsattr` or `auditd`. |
Обнаружение
Monitor for unexpected changes to RC scripts in the /etc/ directory. Monitor process execution resulting from RC scripts for unusual or unknown applications or behavior.
Monitor for /etc/rc.local file creation. Although types of RC scripts vary for each Unix-like distribution, several execute /etc/rc.local if present.
Ссылки
- Sanmillan, I. (2019, May 29). HiddenWasp Malware Stings Targeted Linux Systems. Retrieved June 24, 2019.
- Paul Litvak. (2020, May 4). Kaiji: New Chinese Linux malware turning to Golang. Retrieved December 17, 2020.
- Patrick Wardle. (2014, September). Methods of Malware Persistence on Mac OS X. Retrieved July 5, 2017.
- Iran Threats . (2017, December 5). Flying Kitten to Rocket Kitten, A Case of Ambiguity and Shared Code. Retrieved May 28, 2020.
- 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.
- Asher Langton. (2022, December 9). A Custom Python Backdoor for VMWare ESXi Servers. Retrieved March 26, 2025.
- Apple. (2016, September 13). Startup Items. Retrieved July 11, 2017.
- Apple. (2016, September 13). Daemons and Services Programming Guide - Creating Launch Daemons and Agents. Retrieved February 24, 2021.
- Sygnia Team. (2024, June 3). China-Nexus Threat Group ‘Velvet Ant’ Abuses F5 Load Balancers for Persistence. Retrieved March 14, 2025.
- Mandiant. (2022, May 2). UNC3524: Eye Spy on Your Email. Retrieved August 17, 2023.
- Sandvik, Runa. (2021, October 18). Green Lambert and ATT&CK. Retrieved November 17, 2024.
- Sandvik, Runa. (2021, October 1). Made In America: Green Lambert for OS X. Retrieved March 21, 2022.
- NCSC. (2022, February 23). Cyclops Blink Malware Analysis Report. Retrieved March 3, 2022.
- Patrick Wardle. (n.d.). Mac Malware of 2017. Retrieved September 21, 2018.
Связанные риски
Каталоги
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