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T1546.009 AppCert DLLs

Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by AppCert DLLs loaded into processes. Dynamic-link libraries (DLLs) that are specified in the AppCertDLLs Registry key under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\ are loaded into every process that calls the ubiquitously used application programming interface (API) functions CreateProcess, CreateProcessAsUser, CreateProcessWithLoginW, CreateProcessWithTokenW, or WinExec. 1

Similar to Process Injection, this value can be abused to obtain elevated privileges by causing a malicious DLL to be loaded and run in the context of separate processes on the computer. Malicious AppCert DLLs may also provide persistence by continuously being triggered by API activity.

Item Value
ID T1546.009
Sub-techniques T1546.001, T1546.002, T1546.003, T1546.004, T1546.005, T1546.006, T1546.007, T1546.008, T1546.009, T1546.010, T1546.011, T1546.012, T1546.013, T1546.014, T1546.015, T1546.016
Tactics TA0004, TA0003
Platforms Windows
Permissions required Administrator, SYSTEM
Version 1.0
Created 24 January 2020
Last Modified 10 November 2020

Procedure Examples

ID Name Description
S0196 PUNCHBUGGY PUNCHBUGGY can establish using a AppCertDLLs Registry key.10

Mitigations

ID Mitigation Description
M1038 Execution Prevention Adversaries install new AppCertDLL binaries to execute this technique. Identify and block potentially malicious software executed through AppCertDLLs functionality by using application control 4 tools, like Windows Defender Application Control5, AppLocker, 6 7 or Software Restriction Policies 8 where appropriate. 9

Detection

ID Data Source Data Component
DS0017 Command Command Execution
DS0011 Module Module Load
DS0009 Process OS API Execution
DS0024 Windows Registry Windows Registry Key Modification

References

  1. Hosseini, A. (2017, July 18). Ten Process Injection Techniques: A Technical Survey Of Common And Trending Process Injection Techniques. Retrieved December 7, 2017. ↩

  2. Russinovich, M. (2016, January 4). Autoruns for Windows v13.51. Retrieved June 6, 2016. ↩

  3. Microsoft. (2007, October 24). Windows Sysinternals - AppCertDlls. Retrieved December 18, 2017. ↩

  4. Beechey, J. (2010, December). Application Whitelisting: Panacea or Propaganda?. Retrieved November 18, 2014. ↩

  5. Gorzelany, A., Hall, J., Poggemeyer, L.. (2019, January 7). Windows Defender Application Control. Retrieved July 16, 2019. ↩

  6. Tomonaga, S. (2016, January 26). Windows Commands Abused by Attackers. Retrieved February 2, 2016. ↩

  7. NSA Information Assurance Directorate. (2014, August). Application Whitelisting Using Microsoft AppLocker. Retrieved March 31, 2016. ↩

  8. Corio, C., & Sayana, D. P. (2008, June). Application Lockdown with Software Restriction Policies. Retrieved November 18, 2014. ↩

  9. Microsoft. (2012, June 27). Using Software Restriction Policies and AppLocker Policies. Retrieved April 7, 2016. ↩

  10. Elovitz, S. & Ahl, I. (2016, August 18). Know Your Enemy: New Financially-Motivated & Spear-Phishing Group. Retrieved February 26, 2018. ↩