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T1648 Serverless Execution

Adversaries may abuse serverless computing, integration, and automation services to execute arbitrary code in cloud environments. Many cloud providers offer a variety of serverless resources, including compute engines, application integration services, and web servers.

Adversaries may abuse these resources in various ways as a means of executing arbitrary commands. For example, adversaries may use serverless functions to execute malicious code, such as crypto-mining malware (i.e. Resource Hijacking).6 Adversaries may also create functions that enable further compromise of the cloud environment. For example, an adversary may use the IAM:PassRole permission in AWS or the iam.serviceAccounts.actAs permission in Google Cloud to add Additional Cloud Roles to a serverless cloud function, which may then be able to perform actions the original user cannot.78

Serverless functions can also be invoked in response to cloud events (i.e. Event Triggered Execution), potentially enabling persistent execution over time. For example, in AWS environments, an adversary may create a Lambda function that automatically adds Additional Cloud Credentials to a user and a corresponding CloudWatch events rule that invokes that function whenever a new user is created.2 This is also possible in many cloud-based office application suites. For example, in Microsoft 365 environments, an adversary may create a Power Automate workflow that forwards all emails a user receives or creates anonymous sharing links whenever a user is granted access to a document in SharePoint.31 In Google Workspace environments, they may instead create an Apps Script that exfiltrates a user’s data when they open a file.45

Item Value
ID T1648
Sub-techniques
Tactics TA0002
Platforms IaaS, Office Suite, SaaS
Version 1.2
Created 27 May 2022
Last Modified 15 April 2025

Procedure Examples

ID Name Description
S1091 Pacu Pacu can create malicious Lambda functions.11

Mitigations

ID Mitigation Description
M1036 Account Use Policies Where possible, consider restricting access to and use of serverless functions. For examples, conditional access policies can be applied to users attempting to create workflows in Microsoft Power Automate. Google Apps Scripts that use OAuth can be limited by restricting access to high-risk OAuth scopes.109
M1018 User Account Management Remove permissions to create, modify, or run serverless resources from users that do not explicitly require them.

References

  1. Berk Veral. (2020, March 9). Real-life cybercrime stories from DART, the Microsoft Detection and Response Team. Retrieved May 27, 2022. ↩

  2. Daniel Grzelak. (2016, July 9). Backdooring an AWS account. Retrieved May 27, 2022. ↩

  3. Eric Saraga. (2022, February 2). Using Power Automate for Covert Data Exfiltration in Microsoft 365. Retrieved May 27, 2022. ↩

  4. HackTricks Cloud. (n.d.). GWS - App Scripts. Retrieved July 1, 2024. ↩

  5. L’Hutereau Arnaud. (n.d.). Google Workspace Malicious App Script analysis. Retrieved October 2, 2024. ↩

  6. Matt Muir. (2022, April 6). Cado Discovers Denonia: The First Malware Specifically Targeting Lambda. Retrieved May 27, 2022. ↩

  7. Rhino Security Labs. (n.d.). AWS IAM Privilege Escalation – Methods and Mitigation. Retrieved May 27, 2022. ↩

  8. Spencer Gietzen. (n.d.). Privilege Escalation in Google Cloud Platform – Part 1 (IAM). Retrieved May 27, 2022. ↩

  9. Google Workspace. (2024, March 5). Monitor & restrict data access. Retrieved July 1, 2024. ↩

  10. Microsoft Developer Support. (2020, May 9). Control Access to Power Apps and Power Automate with Azure AD Conditional Access Policies. Retrieved July 1, 2024. ↩

  11. Rhino Security Labs. (2019, August 22). Pacu. Retrieved October 17, 2019. ↩