Signed Binary Proxy Execution: Mshta
Mshta.exe is a utility that executes Microsoft HTML Applications (HTA) files.  HTAs are standalone applications that execute using the same models and technologies of Internet Explorer, but outside of the browser. 
Files may be executed by mshta.exe through an inline script:
They may also be executed directly from URLs:
Mshta.exe can be used to bypass application control solutions that do not account for its potential use. Since mshta.exe executes outside of the Internet Explorer's security context, it also bypasses browser security settings. 
|M1042||Disable or Remove Feature or Program||
Mshta.exe may not be necessary within a given environment since its functionality is tied to older versions of Internet Explorer that have reached end of life.
Use application control configured to block execution of mshta.exe if it is not required for a given system or network to prevent potential misuse by adversaries.
Use process monitoring to monitor the execution and arguments of mshta.exe. Look for mshta.exe executing raw or obfuscated script within the command-line. Compare recent invocations of mshta.exe with prior history of known good arguments and executed .hta files to determine anomalous and potentially adversarial activity. Command arguments used before and after the mshta.exe invocation may also be useful in determining the origin and purpose of the .hta file being executed.
Monitor use of HTA files. If they are not typically used within an environment then execution of them may be suspicious
- Gross, J. (2016, February 23). Operation Dust Storm. Retrieved September 19, 2017.
- McCammon, K. (2015, August 14). Microsoft HTML Application (HTA) Abuse, Part Deux. Retrieved October 27, 2017.
- Berry, A., Galang, L., Jiang, G., Leathery, J., Mohandas, R. (2017, April 11). CVE-2017-0199: In the Wild Attacks Leveraging HTA Handler. Retrieved October 27, 2017.
- Dove, A. (2016, March 23). Fileless Malware – A Behavioural Analysis Of Kovter Persistence. Retrieved December 5, 2017.
- Carr, N., et al. (2017, April 24). FIN7 Evolution and the Phishing LNK. Retrieved April 24, 2017.
- Wikipedia. (2017, October 14). HTML Application. Retrieved October 27, 2017.
- Microsoft. (n.d.). HTML Applications. Retrieved October 27, 2017.
- LOLBAS. (n.d.). Mshta.exe. Retrieved July 31, 2019.
- Dahan, A. (2017, May 24). OPERATION COBALT KITTY: A LARGE-SCALE APT IN ASIA CARRIED OUT BY THE OCEANLOTUS GROUP. Retrieved November 5, 2018.
- Dahan, A. (2017). Operation Cobalt Kitty. Retrieved December 27, 2018.
- CISA, FBI, CNMF. (2020, October 27). https://us-cert.cisa.gov/ncas/alerts/aa20-301a. Retrieved November 4, 2020.
- GReAT. (2019, August 12). Recent Cloud Atlas activity. Retrieved May 8, 2020.
- Alyac. (2019, April 3). Kimsuky Organization Steals Operation Stealth Power. Retrieved August 13, 2019.
- Crowdstrike. (2020, March 2). 2020 Global Threat Report. Retrieved December 11, 2020.
- Magius, J., et al. (2017, July 19). Koadic. Retrieved June 18, 2018.
- F-Secure Labs. (2020, August 18). Lazarus Group Campaign Targeting the Cryptocurrency Vertical. Retrieved September 1, 2020.
- Sierra, E., Iglesias, G.. (2018, April 24). Metamorfo Campaigns Targeting Brazilian Users. Retrieved July 30, 2020.
- Singh, S. et al.. (2018, March 13). Iranian Threat Group Updates Tactics, Techniques and Procedures in Spear Phishing Campaign. Retrieved April 11, 2018.
- Kaspersky Lab's Global Research & Analysis Team. (2018, October 10). MuddyWater expands operations. Retrieved November 2, 2018.
- Counter Threat Unit Research Team. (2019, December 29). BRONZE PRESIDENT Targets NGOs. Retrieved April 13, 2021.
- F-Secure Labs. (2016, July). NANHAISHU RATing the South China Sea. Retrieved July 6, 2018.
- Gannon, M. (2019, February 11). With Upgrades in Delivery and Support Infrastructure, Revenge RAT Malware is a Bigger Threat. Retrieved May 1, 2019.
- Nafisi, R., Lelli, A. (2021, March 4). GoldMax, GoldFinder, and Sibot: Analyzing NOBELIUM’s layered persistence. Retrieved March 8, 2021.
- Rewertz. (2020, April 20). Sidewinder APT Group Campaign Analysis. Retrieved January 29, 2021.
- Rewterz. (2020, June 22). Analysis on Sidewinder APT Group – COVID-19. Retrieved January 29, 2021.
- Duncan, B. (2021, January 7). TA551: Email Attack Campaign Switches from Valak to IcedID. Retrieved March 17, 2021.
- Xiao, C. (2018, September 17). Xbash Combines Botnet, Ransomware, Coinmining in Worm that Targets Linux and Windows. Retrieved November 14, 2018.