Encrypted Channel: Asymmetric Cryptography
Adversaries may employ a known asymmetric encryption algorithm to conceal command and control traffic rather than relying on any inherent protections provided by a communication protocol. Asymmetric cryptography, also known as public key cryptography, uses a keypair per party: one public that can be freely distributed, and one private. Due to how the keys are generated, the sender encrypts data with the receiver’s public key and the receiver decrypts the data with their private key. This ensures that only the intended recipient can read the encrypted data. Common public key encryption algorithms include RSA and ElGamal.
For efficiency, may protocols (including SSL/TLS) use symmetric cryptography once a connection is established, but use asymmetric cryptography to establish or transmit a key. As such, these protocols are classified as Asymmetric Cryptography.
|Network Intrusion Prevention||
Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level.
SSL/TLS inspection can be used to see the contents of encrypted sessions to look for network-based indicators of malware communication protocols.
SSL/TLS inspection is one way of detecting command and control traffic within some encrypted communication channels. SSL/TLS inspection does come with certain risks that should be considered before implementing to avoid potential security issues such as incomplete certificate validation.
In general, analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect communications that do not follow the expected protocol behavior for the port that is being used.
- Windows Defender Advanced Threat Hunting Team. (2016, April 29). PLATINUM: Targeted attacks in South and Southeast Asia. Retrieved February 15, 2018.
- Bitdefender. (2015, December). APT28 Under the Scope. Retrieved February 23, 2017.
- Hromcova, Z. (2019, October). AT COMMANDS, TOR-BASED COMMUNICATIONS: MEET ATTOR, A FANTASY CREATURE AND ALSO A SPY PLATFORM. Retrieved May 6, 2020.
- Mandiant. (n.d.). Appendix C (Digital) - The Malware Arsenal. Retrieved July 18, 2016.
- ESET. (2016, October). En Route with Sednit - Part 2: Observing the Comings and Goings. Retrieved November 21, 2016.
- Matveeva, V. (2017, August 15). Secrets of Cobalt. Retrieved October 10, 2018.
- Faou, M. (2020, May). From Agent.btz to ComRAT v4: A ten-year journey. Retrieved June 15, 2020.
- Slepogin, N. (2017, May 25). Dridex: A History of Evolution. Retrieved May 31, 2019.
- Trend Micro. (2019, January 16). Exploring Emotet's Activities . Retrieved March 25, 2019.
- Schroeder, W., Warner, J., Nelson, M. (n.d.). Github PowerShellEmpire. Retrieved April 28, 2016.
- FireEye Threat Intelligence. (2016, April). Follow the Money: Dissecting the Operations of the Cyber Crime Group FIN6. Retrieved June 1, 2016.
- Elovitz, S. & Ahl, I. (2016, August 18). Know Your Enemy: New Financially-Motivated & Spear-Phishing Group. Retrieved February 26, 2018.
- ESET. (2017, August). Gazing at Gazer: Turla’s new second stage backdoor. Retrieved September 14, 2017.
- Kaspersky Lab's Global Research & Analysis Team. (2017, August 30). Introducing WhiteBear. Retrieved September 21, 2017.
- Cherepanov, A. (2018, October). GREYENERGY A successor to BlackEnergy. Retrieved November 15, 2018.
- Fidelis Threat Research Team. (2016, January 27). Introducing Hi-Zor RAT. Retrieved March 24, 2016.
- Kessem, L., et al. (2017, November 13). New Banking Trojan IcedID Discovered by IBM X-Force Research. Retrieved July 14, 2020.
- Kimayong, P. (2020, June 18). COVID-19 and FMLA Campaigns used to install new IcedID banking malware. Retrieved July 14, 2020.
- Magius, J., et al. (2017, July 19). Koadic. Retrieved June 18, 2018.
- The Cylance Threat Research Team. (2017, March 22). El Machete's Malware Attacks Cut Through LATAM. Retrieved September 13, 2019.
- Erlich, C. (2020, April 3). The Avast Abuser: Metamorfo Banking Malware Hides By Abusing Avast Executable. Retrieved May 26, 2020.
- Davis, S. and Caban, D. (2017, December 19). APT34 - New Targeted Attack in the Middle East. Retrieved December 20, 2017.
- Mercer, W, et al. (2020, April 16). PoetRAT: Python RAT uses COVID-19 lures to target Azerbaijan public and private sectors. Retrieved April 27, 2020.
- Dunwoody, M.. (2017, April 3). Dissecting One of APT29’s Fileless WMI and PowerShell Backdoors (POSHSPY). Retrieved April 5, 2017.
- Singh, S. et al.. (2018, March 13). Iranian Threat Group Updates Tactics, Techniques and Procedures in Spear Phishing Campaign. Retrieved April 11, 2018.
- Nicolas Verdier. (n.d.). Retrieved January 29, 2018.
- Mamedov, O, et al. (2019, July 3). Sodin ransomware exploits Windows vulnerability and processor architecture. Retrieved August 4, 2020.
- Schwarz, D. and Proofpoint Staff. (2019, January 9). ServHelper and FlawedGrace - New malware introduced by TA505. Retrieved May 28, 2019.
- Mercer, W. et al. (2020, June 29). PROMETHIUM extends global reach with StrongPity3 APT. Retrieved July 20, 2020.
- Blasco, J. (2013, March 21). New Sykipot developments [Blog]. Retrieved November 12, 2014.
- Roger Dingledine, Nick Mathewson and Paul Syverson. (2004). Tor: The Second-Generation Onion Router. Retrieved December 21, 2017.
- Secureworks. (2019, July 24). Updated Karagany Malware Targets Energy Sector. Retrieved August 12, 2020.
- Horejsi, J., et al. (2018, March 14). Tropic Trooper’s New Strategy. Retrieved November 9, 2018.
- Chen, J.. (2020, May 12). Tropic Trooper’s Back: USBferry Attack Targets Air gapped Environments. Retrieved May 20, 2020.
- US-CERT. (2017, November 22). Alert (TA17-318B): HIDDEN COBRA – North Korean Trojan: Volgmer. Retrieved December 7, 2017.
- Counter Threat Unit Research Team. (2017, May 18). WCry Ransomware Analysis. Retrieved March 26, 2019.
- CISA. (2020, July 16). MAR-10296782-3.v1 – WELLMAIL. Retrieved September 29, 2020.
- National Cyber Security Centre. (2020, July 16). Advisory: APT29 targets COVID-19 vaccine development. Retrieved September 29, 2020.
- PWC. (2020, July 16). How WellMess malware has been used to target COVID-19 vaccines. Retrieved September 24, 2020.
- PWC. (2020, August 17). WellMess malware: analysis of its Command and Control (C2) server. Retrieved September 29, 2020.
- CISA. (2020, July 16). MAR-10296782-2.v1 – WELLMESS. Retrieved September 24, 2020.
- Belcher, P.. (2016, July 28). Tunnel of Gov: DNC Hack and the Russian XTunnel. Retrieved August 3, 2016.
- ESET. (2018, November 20). Sednit: What’s going on with Zebrocy?. Retrieved February 12, 2019.
- ESET Research. (2019, May 22). A journey to Zebrocy land. Retrieved June 20, 2019.
- Butler, M. (2013, November). Finding Hidden Threats by Decrypting SSL. Retrieved April 5, 2016.
- Dormann, W. (2015, March 13). The Risks of SSL Inspection. Retrieved April 5, 2016.
- Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.