Command and Scripting Interpreter: AppleScript
Other sub-techniques of Command and Scripting Interpreter (12)
Adversaries may abuse AppleScript for execution. AppleScript is a macOS scripting language designed to control applications and parts of the OS via inter-application messages called AppleEvents.(Citation: Apple AppleScript) These AppleEvent messages can be sent independently or easily scripted with AppleScript. These events can locate open windows, send keystrokes, and interact with almost any open application locally or remotely.
Scripts can be run from the command-line via osascript /path/to/script
or osascript -e "script here"
. Aside from the command line, scripts can be executed in numerous ways including Mail rules, Calendar.app alarms, and Automator workflows. AppleScripts can also be executed as plain text shell scripts by adding #!/usr/bin/osascript
to the start of the script file.(Citation: SentinelOne AppleScript)
AppleScripts do not need to call osascript
to execute. However, they may be executed from within mach-O binaries by using the macOS Native APIs NSAppleScript
or OSAScript
, both of which execute code independent of the /usr/bin/osascript
command line utility.
Adversaries may abuse AppleScript to execute various behaviors, such as interacting with an open SSH connection, moving to remote machines, and even presenting users with fake dialog boxes. These events cannot start applications remotely (they can start them locally), but they can interact with applications if they're already running remotely. On macOS 10.10 Yosemite and higher, AppleScript has the ability to execute Native APIs, which otherwise would require compilation and execution in a mach-O binary file format.(Citation: SentinelOne macOS Red Team) Since this is a scripting language, it can be used to launch more common techniques as well such as a reverse shell via Python.(Citation: Macro Malware Targets Macs)
Procedure Examples |
|
Name | Description |
---|---|
Dok |
Dok uses AppleScript to create a login item for persistence.(Citation: objsee mac malware 2017) |
ThiefQuest |
ThiefQuest uses AppleScript's |
Bundlore |
Bundlore can use AppleScript to inject malicious JavaScript into a browser.(Citation: MacKeeper Bundlore Apr 2019) |
Cuckoo Stealer |
Cuckoo Stealer can use osascript to generate a password-stealing prompt, duplicate files and folders, and set environmental variables.(Citation: Kandji Cuckoo April 2024)(Citation: SentinelOne Cuckoo Stealer May 2024) |
macOS.OSAMiner |
macOS.OSAMiner has used `osascript` to call itself via the `do shell script` command in the Launch Agent `.plist` file.(Citation: SentinelLabs reversing run-only applescripts 2021) |
Mitigations |
|
Mitigation | Description |
---|---|
Code Signing |
Code Signing is a security process that ensures the authenticity and integrity of software by digitally signing executables, scripts, and other code artifacts. It prevents untrusted or malicious code from executing by verifying the digital signatures against trusted sources. Code signing protects against tampering, impersonation, and distribution of unauthorized or malicious software, forming a critical defense against supply chain and software exploitation attacks. This mitigation can be implemented through the following measures: Enforce Signed Code Execution: - Implementation: Configure operating systems (e.g., Windows with AppLocker or Linux with Secure Boot) to allow only signed code to execute. - Use Case: Prevent the execution of malicious PowerShell scripts by requiring all scripts to be signed with a trusted certificate. Vendor-Signed Driver Enforcement: - Implementation: Enable kernel-mode code signing to ensure that only drivers signed by trusted vendors can be loaded. - Use Case: A malicious driver attempting to modify system memory fails to load because it lacks a valid signature. Certificate Revocation Management: - Implementation: Use Online Certificate Status Protocol (OCSP) or Certificate Revocation Lists (CRLs) to block certificates associated with compromised or deprecated code. - Use Case: A compromised certificate used to sign a malicious update is revoked, preventing further execution of the software. Third-Party Software Verification: - Implementation: Require software from external vendors to be signed with valid certificates before deployment. - Use Case: An organization only deploys signed and verified third-party software to prevent supply chain attacks. Script Integrity in CI/CD Pipelines: - Implementation: Integrate code signing into CI/CD pipelines to sign and verify code artifacts before production release. - Use Case: A software company ensures that all production builds are signed, preventing tampered builds from reaching customers. **Key Components of Code Signing** - Digital Signature Verification: Verifies the authenticity of code by ensuring it was signed by a trusted entity. - Certificate Management: Uses Public Key Infrastructure (PKI) to manage signing certificates and revocation lists. - Enforced Policy for Unsigned Code: Prevents the execution of unsigned or untrusted binaries and scripts. - Hash Integrity Check: Confirms that code has not been altered since signing by comparing cryptographic hashes. |
Execution Prevention |
Prevent the execution of unauthorized or malicious code on systems by implementing application control, script blocking, and other execution prevention mechanisms. This ensures that only trusted and authorized code is executed, reducing the risk of malware and unauthorized actions. This mitigation can be implemented through the following measures: Application Control: - Use Case: Use tools like AppLocker or Windows Defender Application Control (WDAC) to create whitelists of authorized applications and block unauthorized ones. On Linux, use tools like SELinux or AppArmor to define mandatory access control policies for application execution. - Implementation: Allow only digitally signed or pre-approved applications to execute on servers and endpoints. (e.g., `New-AppLockerPolicy -PolicyType Enforced -FilePath "C:\Policies\AppLocker.xml"`) Script Blocking: - Use Case: Use script control mechanisms to block unauthorized execution of scripts, such as PowerShell or JavaScript. Web Browsers: Use browser extensions or settings to block JavaScript execution from untrusted sources. - Implementation: Configure PowerShell to enforce Constrained Language Mode for non-administrator users. (e.g., `Set-ExecutionPolicy AllSigned`) Executable Blocking: - Use Case: Prevent execution of binaries from suspicious locations, such as `%TEMP%` or `%APPDATA%` directories. - Implementation: Block execution of `.exe`, `.bat`, or `.ps1` files from user-writable directories. Dynamic Analysis Prevention: - Use Case: Use behavior-based execution prevention tools to identify and block malicious activity in real time. - Implemenation: Employ EDR solutions that analyze runtime behavior and block suspicious code execution. |
Detection
Monitor for execution of AppleScript through osascript
and usage of the NSAppleScript
and OSAScript
APIs that may be related to other suspicious behavior occurring on the system. Scripts are likely to perform actions with various effects on a system that may generate events, depending on the types of monitoring used. Monitor processes and command-line arguments for script execution and subsequent behavior. Actions may be related to network and system information Discovery, Collection, or other scriptable post-compromise behaviors and could be used as indicators of detection leading back to the source script.
Understanding standard usage patterns is important to avoid a high number of false positives. If scripting is restricted for normal users, then any attempts to enable scripts running on a system would be considered suspicious. If scripts are not commonly used on a system, but enabled, scripts running out of cycle from patching or other administrator functions are suspicious. Scripts should be captured from the file system when possible to determine their actions and intent.
References
- Yerko Grbic. (2017, February 14). Macro Malware Targets Macs. Retrieved July 8, 2017.
- Phil Stokes. (2020, March 16). How Offensive Actors Use AppleScript For Attacking macOS. Retrieved July 17, 2020.
- Phil Stokes. (2019, December 5). macOS Red Team: Calling Apple APIs Without Building Binaries. Retrieved July 17, 2020.
- Apple. (2016, January 25). Introduction to AppleScript Language Guide. Retrieved March 28, 2020.
- Steven Sande. (2013, December 23). AppleScript and Automator gain new features in OS X Mavericks. Retrieved September 21, 2018.
- Patrick Wardle. (n.d.). Mac Malware of 2017. Retrieved September 21, 2018.
- Patrick Wardle. (2020, June 29). OSX.EvilQuest Uncovered part i: infection, persistence, and more!. Retrieved March 18, 2021.
- Sushko, O. (2019, April 17). macOS Bundlore: Mac Virus Bypassing macOS Security Features. Retrieved June 30, 2020.
- Stokes, P. (2024, May 9). macOS Cuckoo Stealer | Ensuring Detection and Defense as New Samples Rapidly Emerge. Retrieved August 20, 2024.
- Kohler, A. and Lopez, C. (2024, April 30). Malware: Cuckoo Behaves Like Cross Between Infostealer and Spyware. Retrieved August 20, 2024.
- Phil Stokes. (2021, January 11). FADE DEAD | Adventures in Reversing Malicious Run-Only AppleScripts. Retrieved September 29, 2022.
Связанные риски
Каталоги
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