Subvert Trust Controls: Code Signing

Adversaries may create, acquire, or steal code signing materials to sign their malware or tools. Code signing provides a level of authenticity on a binary from the developer and a guarantee that the binary has not been tampered with. [1] The certificates used during an operation may be created, acquired, or stolen by the adversary. [2] [3] Unlike Invalid Code Signature, this activity will result in a valid signature.

Code signing to verify software on first run can be used on modern Windows and macOS systems. It is not used on Linux due to the decentralized nature of the platform. [1][4]

Code signing certificates may be used to bypass security policies that require signed code to execute on a system.

ID: T1553.002
Sub-technique of:  T1553
Tactic: Defense Evasion
Platforms: Windows, macOS
Defense Bypassed: Windows User Account Control
Version: 1.1
Created: 05 February 2020
Last Modified: 22 September 2022

Procedure Examples

ID Name Description
S0504 Anchor

Anchor has been signed with valid certificates to evade detection by security tools.[5]

S0584 AppleJeus

AppleJeus has used a valid digital signature from Sectigo to appear legitimate.[6]

G0096 APT41

APT41 leveraged code-signing certificates to sign malware when targeting both gaming and non-gaming organizations.[7][8]

S0475 BackConfig

BackConfig has been signed with self signed digital certificates mimicking a legitimate software company.[9]

S0234 Bandook

Bandook was signed with valid Certum certificates.[10]

S0534 Bazar

Bazar has been signed with fake certificates including those appearing to be from VB CORPORATE PTY. LTD.[11]

S1070 Black Basta

The Black Basta dropper has been digitally signed with a certificate issued by Akeo Consulting for legitimate executables used for creating bootable USB drives.[12]

S0520 BLINDINGCAN

BLINDINGCAN has been signed with code-signing certificates such as CodeRipper.[13]

S0415 BOOSTWRITE

BOOSTWRITE has been signed by a valid CA.[14]

C0015 C0015

For C0015, the threat actors used DLL files that had invalid certificates.[15]

S0144 ChChes

ChChes samples were digitally signed with a certificate originally used by Hacking Team that was later leaked and subsequently revoked.[16][17][18]

S0611 Clop

Clop can use code signing to evade detection.[19]

S0154 Cobalt Strike

Cobalt Strike can use self signed Java applets to execute signed applet attacks.[20][21]

G0052 CopyKittens

CopyKittens digitally signed an executable with a stolen certificate from legitimate company AI Squared.[22]

S0527 CSPY Downloader

CSPY Downloader has come signed with revoked certificates.[23]

G0012 Darkhotel

Darkhotel has used code-signing certificates on its malware that are either forged due to weak keys or stolen. Darkhotel has also stolen certificates and signed backdoors and downloaders with them.[24][25]

S0187 Daserf

Some Daserf samples were signed with a stolen digital certificate.[26]

S0377 Ebury

Ebury has installed a self-signed RPM package mimicking the original system package on RPM based systems.[27]

S0624 Ecipekac

Ecipekac has used a valid, legitimate digital signature to evade detection.[28]

G1003 Ember Bear

Ember Bear has used stolen certificates from Electrum Technologies GmbH to sign payloads.[29]

S0091 Epic

Turla has used valid digital certificates from Sysprint AG to sign its Epic dropper.[30]

G0037 FIN6

FIN6 has used Comodo code-signing certificates.[31]

G0046 FIN7

FIN7 has signed Carbanak payloads with legally purchased code signing certificates. FIN7 has also digitally signed their phishing documents, backdoors and other staging tools to bypass security controls.[32][33]

G0093 GALLIUM

GALLIUM has used stolen certificates to sign its tools including those from Whizzimo LLC.[34]

S0168 Gazer

Gazer versions are signed with various valid certificates; one was likely faked and issued by Comodo for "Solid Loop Ltd," and another was issued for "Ultimate Computer Support Ltd."[35][36]

S0342 GreyEnergy

GreyEnergy digitally signs the malware with a code-signing certificate.[37]

S0170 Helminth

Helminth samples have been signed with legitimate, compromised code signing certificates owned by software company AI Squared.[38]

S0697 HermeticWiper

The HermeticWiper executable has been signed with a legitimate certificate issued to Hermetica Digital Ltd.[39][40][41][42]

S0698 HermeticWizard

HermeticWizard has been signed by valid certificates assigned to Hermetica Digital.[43]

S0163 Janicab

Janicab used a valid AppleDeveloperID to sign the code to get past security restrictions.[44]

G0094 Kimsuky

Kimsuky has signed files with the name EGIS CO,. Ltd..[45]

G0032 Lazarus Group

Lazarus Group has digitally signed malware and utilities to evade detection.[46]

G0065 Leviathan

Leviathan has used stolen code signing certificates to sign malware.[47][48]

S0372 LockerGoga

LockerGoga has been signed with stolen certificates in order to make it look more legitimate.[49]

G1014 LuminousMoth

LuminousMoth has signed their malware with a valid digital signature.[50]

G0045 menuPass

menuPass has resized and added data to the certificate table to enable the signing of modified files with legitimate signatures.[28]

S0455 Metamorfo

Metamorfo has digitally signed executables using AVAST Software certificates.[51]

G0021 Molerats

Molerats has used forged Microsoft code-signing certificates on malware.[52]

S0284 More_eggs

More_eggs has used a signed binary shellcode loader and a signed Dynamic Link Library (DLL) to create a reverse shell.[31]

G1009 Moses Staff

Moses Staff has used signed drivers from an open source tool called DiskCryptor to evade detection.[53]

S0210 Nerex

Nerex drops a signed Microsoft DLL to disk.[54]

C0022 Operation Dream Job

During Operation Dream Job, Lazarus Group digitally signed their own malware to evade detection.[55]

C0006 Operation Honeybee

During Operation Honeybee, the threat actors deployed the MaoCheng dropper with a stolen Adobe Systems digital signature.[56]

G0040 Patchwork

Patchwork has signed malware with self-signed certificates from fictitious and spoofed legitimate software companies.[9]

S0501 PipeMon

PipeMon, its installer, and tools are signed with stolen code-signing certificates.[57]

G0056 PROMETHIUM

PROMETHIUM has signed code with self-signed certificates.[58]

S0650 QakBot

QakBot can use signed loaders to evade detection.[59][60]

S0262 QuasarRAT

A QuasarRAT .dll file is digitally signed by a certificate from AirVPN.[61]

S0148 RTM

RTM samples have been signed with a code-signing certificates.[62]

G1015 Scattered Spider

Scattered Spider has used self-signed and stolen certificates originally issued to NVIDIA and Global Software LLC.[63]

G0091 Silence

Silence has used a valid certificate to sign their primary loader Silence.Downloader (aka TrueBot).[64]

C0024 SolarWinds Compromise

During the SolarWinds Compromise, APT29 was able to get SUNBURST signed by SolarWinds code signing certificates by injecting the malware into the SolarWinds Orion software lifecycle.[65]

S0646 SpicyOmelette

SpicyOmelette has been signed with valid digital certificates.[66]

S0491 StrongPity

StrongPity has been signed with self-signed certificates.[58]

S0603 Stuxnet

Stuxnet used a digitally signed driver with a compromised Realtek certificate.[67]

G0039 Suckfly

Suckfly has used stolen certificates to sign its malware.[68]

S0559 SUNBURST

SUNBURST was digitally signed by SolarWinds from March - May 2020.[65]

S0663 SysUpdate

SysUpdate has been signed with stolen digital certificates.[69]

G0092 TA505

TA505 has signed payloads with code signing certificates from Thawte and Sectigo.[70][71][72]

S0266 TrickBot

TrickBot has come with a signed downloader component.[5]

G0044 Winnti Group

Winnti Group used stolen certificates to sign its malware.[73]

G0102 Wizard Spider

Wizard Spider has used Digicert code-signing certificates for some of its malware.[74]

Mitigations

This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.

Detection

ID Data Source Data Component Detects
DS0022 File File Metadata

Collect and analyze signing certificate metadata on software that executes within the environment to look for unusual certificate characteristics and outliers.

References

  1. Wikipedia. (2015, November 10). Code Signing. Retrieved March 31, 2016.
  2. Ladikov, A. (2015, January 29). Why You Shouldn’t Completely Trust Files Signed with Digital Certificates. Retrieved March 31, 2016.
  3. Shinotsuka, H. (2013, February 22). How Attackers Steal Private Keys from Digital Certificates. Retrieved March 31, 2016.
  4. Howard Oakley. (2020, November 16). Checks on executable code in Catalina and Big Sur: a first draft. Retrieved September 21, 2022.
  5. Dahan, A. et al. (2019, December 11). DROPPING ANCHOR: FROM A TRICKBOT INFECTION TO THE DISCOVERY OF THE ANCHOR MALWARE. Retrieved September 10, 2020.
  6. Cybersecurity and Infrastructure Security Agency. (2021, February 21). AppleJeus: Analysis of North Korea’s Cryptocurrency Malware. Retrieved March 1, 2021.
  7. Fraser, N., et al. (2019, August 7). Double DragonAPT41, a dual espionage and cyber crime operation APT41. Retrieved September 23, 2019.
  8. Rostovcev, N. (2021, June 10). Big airline heist APT41 likely behind a third-party attack on Air India. Retrieved August 26, 2021.
  9. Hinchliffe, A. and Falcone, R. (2020, May 11). Updated BackConfig Malware Targeting Government and Military Organizations in South Asia. Retrieved June 17, 2020.
  10. Check Point. (2020, November 26). Bandook: Signed & Delivered. Retrieved May 31, 2021.
  11. Cybereason Nocturnus. (2020, July 16). A BAZAR OF TRICKS: FOLLOWING TEAM9’S DEVELOPMENT CYCLES. Retrieved November 18, 2020.
  12. Check Point. (2022, October 20). BLACK BASTA AND THE UNNOTICED DELIVERY. Retrieved March 8, 2023.
  13. US-CERT. (2020, August 19). MAR-10295134-1.v1 – North Korean Remote Access Trojan: BLINDINGCAN. Retrieved August 19, 2020.
  14. Carr, N, et all. (2019, October 10). Mahalo FIN7: Responding to the Criminal Operators’ New Tools and Techniques. Retrieved October 11, 2019.
  15. DFIR Report. (2021, November 29). CONTInuing the Bazar Ransomware Story. Retrieved September 29, 2022.
  16. Miller-Osborn, J. and Grunzweig, J.. (2017, February 16). menuPass Returns with New Malware and New Attacks Against Japanese Academics and Organizations. Retrieved March 1, 2017.
  17. Nakamura, Y.. (2017, February 17). ChChes - Malware that Communicates with C&C Servers Using Cookie Headers. Retrieved March 1, 2017.
  18. PwC and BAE Systems. (2017, April). Operation Cloud Hopper: Technical Annex. Retrieved April 13, 2017.
  19. Santos, D. (2021, April 13). Threat Assessment: Clop Ransomware. Retrieved July 30, 2021.
  20. Mavis, N. (2020, September 21). The Art and Science of Detecting Cobalt Strike. Retrieved April 6, 2021.
  21. Strategic Cyber LLC. (2020, November 5). Cobalt Strike: Advanced Threat Tactics for Penetration Testers. Retrieved April 13, 2021.
  22. ClearSky Cyber Security and Trend Micro. (2017, July). Operation Wilted Tulip: Exposing a cyber espionage apparatus. Retrieved August 21, 2017.
  23. Dahan, A. et al. (2020, November 2). Back to the Future: Inside the Kimsuky KGH Spyware Suite. Retrieved November 6, 2020.
  24. Kaspersky Lab's Global Research and Analysis Team. (2014, November). The Darkhotel APT A Story of Unusual Hospitality. Retrieved November 12, 2014.
  25. Kaspersky Lab's Global Research & Analysis Team. (2015, August 10). Darkhotel's attacks in 2015. Retrieved November 2, 2018.
  26. DiMaggio, J. (2016, April 28). Tick cyberespionage group zeros in on Japan. Retrieved July 16, 2018.
  27. M.Léveillé, M.. (2014, February 21). An In-depth Analysis of Linux/Ebury. Retrieved April 19, 2019.
  28. GREAT. (2021, March 30). APT10: sophisticated multi-layered loader Ecipekac discovered in A41APT campaign. Retrieved June 17, 2021.
  29. Unit 42. (2022, February 25). Spear Phishing Attacks Target Organizations in Ukraine, Payloads Include the Document Stealer OutSteel and the Downloader SaintBot. Retrieved June 9, 2022.
  30. Kaspersky Lab's Global Research and Analysis Team. (2014, August 7). The Epic Turla Operation: Solving some of the mysteries of Snake/Uroburos. Retrieved December 11, 2014.
  31. Villadsen, O.. (2019, August 29). More_eggs, Anyone? Threat Actor ITG08 Strikes Again. Retrieved September 16, 2019.
  32. Bennett, J., Vengerik, B. (2017, June 12). Behind the CARBANAK Backdoor. Retrieved June 11, 2018.
  33. Carr, N., et al. (2018, August 01). On the Hunt for FIN7: Pursuing an Enigmatic and Evasive Global Criminal Operation. Retrieved August 23, 2018.
  34. MSTIC. (2019, December 12). GALLIUM: Targeting global telecom. Retrieved January 13, 2021.
  35. ESET. (2017, August). Gazing at Gazer: Turla’s new second stage backdoor. Retrieved September 14, 2017.
  36. Kaspersky Lab's Global Research & Analysis Team. (2017, August 30). Introducing WhiteBear. Retrieved September 21, 2017.
  37. Cherepanov, A. (2018, October). GREYENERGY A successor to BlackEnergy. Retrieved November 15, 2018.
  1. ClearSky Cybersecurity. (2017, January 5). Iranian Threat Agent OilRig Delivers Digitally Signed Malware, Impersonates University of Oxford. Retrieved May 3, 2017.
  2. Symantec Threat Hunter Team. (2022, February 24). Ukraine: Disk-wiping Attacks Precede Russian Invasion. Retrieved March 25, 2022.
  3. Thomas, W. et al. (2022, February 25). CrowdStrike Falcon Protects from New Wiper Malware Used in Ukraine Cyberattacks. Retrieved March 25, 2022.
  4. ESET. (2022, February 24). HermeticWiper: New data wiping malware hits Ukraine. Retrieved March 25, 2022.
  5. Dani, M. (2022, March 1). Ukrainian Targets Hit by HermeticWiper, New Datawiper Malware. Retrieved March 25, 2022.
  6. ESET. (2022, March 1). IsaacWiper and HermeticWizard: New wiper and worm targetingUkraine. Retrieved April 10, 2022.
  7. Thomas. (2013, July 15). New signed malware called Janicab. Retrieved July 17, 2017.
  8. ThreatConnect. (2020, September 28). Kimsuky Phishing Operations Putting In Work. Retrieved October 30, 2020.
  9. Saini, A. and Hossein, J. (2022, January 27). North Korea’s Lazarus APT leverages Windows Update client, GitHub in latest campaign. Retrieved January 27, 2022.
  10. FireEye. (2018, March 16). Suspected Chinese Cyber Espionage Group (TEMP.Periscope) Targeting U.S. Engineering and Maritime Industries. Retrieved April 11, 2018.
  11. Plan, F., et al. (2019, March 4). APT40: Examining a China-Nexus Espionage Actor. Retrieved March 18, 2019.
  12. Greenberg, A. (2019, March 25). A Guide to LockerGoga, the Ransomware Crippling Industrial Firms. Retrieved July 17, 2019.
  13. Lechtik, M, and etl. (2021, July 14). LuminousMoth APT: Sweeping attacks for the chosen few. Retrieved October 20, 2022.
  14. Erlich, C. (2020, April 3). The Avast Abuser: Metamorfo Banking Malware Hides By Abusing Avast Executable. Retrieved May 26, 2020.
  15. Villeneuve, N., Haq, H., Moran, N. (2013, August 23). OPERATION MOLERATS: MIDDLE EAST CYBER ATTACKS USING POISON IVY. Retrieved April 1, 2016.
  16. Checkpoint Research. (2021, November 15). Uncovering MosesStaff techniques: Ideology over Money. Retrieved August 11, 2022.
  17. Ladley, F. (2012, May 15). Backdoor.Nerex. Retrieved February 23, 2018.
  18. Breitenbacher, D and Osis, K. (2020, June 17). OPERATION IN(TER)CEPTION: Targeted Attacks Against European Aerospace and Military Companies. Retrieved December 20, 2021.
  19. Sherstobitoff, R. (2018, March 02). McAfee Uncovers Operation Honeybee, a Malicious Document Campaign Targeting Humanitarian Aid Groups. Retrieved May 16, 2018.
  20. Tartare, M. et al. (2020, May 21). No “Game over” for the Winnti Group. Retrieved August 24, 2020.
  21. Tudorica, R. et al. (2020, June 30). StrongPity APT - Revealing Trojanized Tools, Working Hours and Infrastructure. Retrieved July 20, 2020.
  22. Morrow, D. (2021, April 15). The rise of QakBot. Retrieved September 27, 2021.
  23. Vilkomir-Preisman, S. (2022, August 18). Beating Black Basta Ransomware. Retrieved March 8, 2023.
  24. Meltzer, M, et al. (2018, June 07). Patchwork APT Group Targets US Think Tanks. Retrieved July 16, 2018.
  25. Faou, M. and Boutin, J. (2017, February). Read The Manual: A Guide to the RTM Banking Trojan. Retrieved March 9, 2017.
  26. CrowdStrike. (2023, January 10). SCATTERED SPIDER Exploits Windows Security Deficiencies with Bring-Your-Own-Vulnerable-Driver Tactic in Attempt to Bypass Endpoint Security. Retrieved July 5, 2023.
  27. Group-IB. (2019, August). Silence 2.0: Going Global. Retrieved May 5, 2020.
  28. FireEye. (2020, December 13). Highly Evasive Attacker Leverages SolarWinds Supply Chain to Compromise Multiple Global Victims With SUNBURST Backdoor. Retrieved January 4, 2021.
  29. CTU. (2018, September 27). Cybercriminals Increasingly Trying to Ensnare the Big Financial Fish. Retrieved September 20, 2021.
  30. Nicolas Falliere, Liam O Murchu, Eric Chien 2011, February W32.Stuxnet Dossier (Version 1.4) Retrieved. 2017/09/22
  31. DiMaggio, J. (2016, March 15). Suckfly: Revealing the secret life of your code signing certificates. Retrieved August 3, 2016.
  32. Daniel Lunghi. (2023, March 1). Iron Tiger’s SysUpdate Reappears, Adds Linux Targeting. Retrieved March 20, 2023.
  33. Salem, E. (2019, April 25). Threat Actor TA505 Targets Financial Enterprises Using LOLBins and a New Backdoor Malware. Retrieved May 28, 2019.
  34. Vilkomir-Preisman, S. (2019, April 2). New ServHelper Variant Employs Excel 4.0 Macro to Drop Signed Payload. Retrieved May 28, 2019.
  35. Hiroaki, H. and Lu, L. (2019, June 12). Shifting Tactics: Breaking Down TA505 Group’s Use of HTML, RATs and Other Techniques in Latest Campaigns. Retrieved May 29, 2020.
  36. Kaspersky Lab's Global Research and Analysis Team. (2013, April 11). Winnti. More than just a game. Retrieved February 8, 2017.
  37. The DFIR Report. (2020, November 5). Ryuk Speed Run, 2 Hours to Ransom. Retrieved November 6, 2020.