Skip to content

T1176.001 Browser Extensions

Adversaries may abuse internet browser extensions to establish persistent access to victim systems. Browser extensions or plugins are small programs that can add functionality to and customize aspects of internet browsers. They can be installed directly via a local file or custom URL or through a browser’s app store - an official online platform where users can browse, install, and manage extensions for a specific web browser. Extensions generally inherit the web browser’s permissions previously granted.134

Malicious extensions can be installed into a browser through malicious app store downloads masquerading as legitimate extensions, through social engineering, or by an adversary that has already compromised a system. Security can be limited on browser app stores, so it may not be difficult for malicious extensions to defeat automated scanners.6 Depending on the browser, adversaries may also manipulate an extension’s update url to install updates from an adversary-controlled server or manipulate the mobile configuration file to silently install additional extensions.

Adversaries may abuse how chromium-based browsers load extensions by modifying or replacing the Preferences and/or Secure Preferences files to silently install malicious extensions. When the browser is not running, adversaries can alter these files, ensuring the extension is loaded, granted desired permissions, and will persist in browser sessions. This method does not require user consent and extensions are silently loaded in the background from disk or from the browser’s trusted store.1

Previous to macOS 11, adversaries could silently install browser extensions via the command line using the profiles tool to install malicious .mobileconfig files. In macOS 11+, the use of the profiles tool can no longer install configuration profiles; however, .mobileconfig files can be planted and installed with user interaction.3

Once the extension is installed, it can browse to websites in the background, steal all information that a user enters into a browser (including credentials), and be used as an installer for a RAT for persistence.2598

There have also been instances of botnets using a persistent backdoor through malicious Chrome extensions for Command and Control.127 Adversaries may also use browser extensions to modify browser permissions and components, privacy settings, and other security controls for Defense Evasion.1110

Item Value
ID T1176.001
Sub-techniques T1176.001, T1176.002
Tactics TA0003
Platforms Linux, Windows, macOS
Version 1.1
Created 30 March 2025
Last Modified 22 September 2025

Procedure Examples

ID Name Description
S0482 Bundlore Bundlore can install malicious browser extensions that are used to hijack user searches.21
S0531 Grandoreiro Grandoreiro can use malicious browser extensions to steal cookies and other user information.20
G0094 Kimsuky Kimsuky has used Google Chrome browser extensions to infect victims and to steal passwords and cookies.2322
S1213 Lumma Stealer Lumma Stealer has installed a malicious browser extension to target Google Chrome, Microsoft Edge, Opera and Brave browsers for the purpose of stealing data.18
S1122 Mispadu Mispadu utilizes malicious Google Chrome browser extensions to steal financial data.15
S0402 OSX/Shlayer OSX/Shlayer can install malicious Safari browser extensions to serve ads.1716
S1201 TRANSLATEXT TRANSLATEXT has the ability to capture credentials, cookies, browser screenshots, etc. and to exfiltrate data.19

Mitigations

ID Mitigation Description
M1047 Audit Ensure extensions that are installed are the intended ones, as many malicious extensions will masquerade as legitimate ones.
M1038 Execution Prevention Set a browser extension allow or deny list as appropriate for your security policy.14
M1033 Limit Software Installation Only install browser extensions from trusted sources that can be verified. Browser extensions for some browsers can be controlled through Group Policy. Change settings to prevent the browser from installing extensions without sufficient permissions.
M1051 Update Software Ensure operating systems and browsers are using the most current version.
M1017 User Training Close out all browser sessions when finished using them to prevent any potentially malicious extensions from continuing to run.

References

  1. Pulsedive Threat Research. (2025, March 21). Rilide - An Information Stealing Browser Extension. Retrieved September 22, 2025. ↩

  2. Brinkmann, M. (2017, September 19). First Chrome extension with JavaScript Crypto Miner detected. Retrieved November 16, 2017. ↩

  3. Chris Ross. (2019, February 8). No Place Like Chrome. Retrieved April 27, 2021. ↩

  4. Chrome. (n.d.). What are Extensions?. Retrieved November 16, 2017. ↩

  5. De Tore, M., Warner, J. (2018, January 15). MALICIOUS CHROME EXTENSIONS ENABLE CRIMINALS TO IMPACT OVER HALF A MILLION USERS AND GLOBAL BUSINESSES. Retrieved January 17, 2018. ↩

  6. Jagpal, N., et al. (2015, August). Trends and Lessons from Three Years Fighting Malicious Extensions. Retrieved November 17, 2017. ↩

  7. Kjaer, M. (2016, July 18). Malware in the browser: how you might get hacked by a Chrome extension. Retrieved September 12, 2024. ↩

  8. Marinho, R. (n.d.). “Catch-All” Google Chrome Malicious Extension Steals All Posted Data. Retrieved November 16, 2017.) ↩

  9. Marinho, R. (n.d.). (Banker(GoogleChromeExtension)).targeting. Retrieved November 18, 2017. ↩

  10. Microsoft Threat Intelligence. (2020, December 10). Widespread malware campaign seeks to silently inject ads into search results, affects multiple browsers. Retrieved February 26, 2024. ↩

  11. Raggi, Michael. Proofpoint Threat Research Team. (2021, February 25). TA413 Leverages New FriarFox Browser Extension to Target the Gmail Accounts of Global Tibetan Organizations. Retrieved November 17, 2024. ↩

  12. Vachon, F., Faou, M. (2017, July 20). Stantinko: A massive adware campaign operating covertly since 2012. Retrieved November 16, 2017. ↩

  13. Wikipedia. (2017, October 8). Browser Extension. Retrieved January 11, 2018. ↩

  14. Mohta, A. (n.d.). Block Chrome Extensions using Google Chrome Group Policy Settings. Retrieved January 10, 2018. ↩

  15. ESET Security. (2019, November 19). Mispadu: Advertisement for a discounted Unhappy Meal. Retrieved March 13, 2024. ↩

  16. Reed, Thomas. (2018, April 24). New Crossrider variant installs configuration profiles on Macs. Retrieved September 6, 2019. ↩

  17. Vrijenhoek, Jay. (2018, April 24). New OSX/Shlayer Malware Variant Found Using a Dirty New Trick. Retrieved September 6, 2019. ↩

  18. Cybereaon Security Services Team. (n.d.). Your Data Is Under New Lummanagement: The Rise of LummaStealer. Retrieved March 22, 2025. ↩

  19. Park, S. (2024, June 27). Kimsuky deploys TRANSLATEXT to target South Korean academia. Retrieved October 14, 2024. ↩

  20. Abramov, D. (2020, April 13). Grandoreiro Malware Now Targeting Banks in Spain. Retrieved November 12, 2020. ↩

  21. Sushko, O. (2019, April 17). macOS Bundlore: Mac Virus Bypassing macOS Security Features. Retrieved June 30, 2020. ↩

  22. ASERT team. (2018, December 5). STOLEN PENCIL Campaign Targets Academia. Retrieved February 5, 2019. ↩

  23. Cimpanu, C.. (2018, December 5). Cyber-espionage group uses Chrome extension to infect victims. Retrieved August 26, 2019. ↩