Custom Cryptographic Protocol
Adversaries may use a custom cryptographic protocol or algorithm to hide command and control traffic. A simple scheme, such as XOR-ing the plaintext with a fixed key, will produce a very weak ciphertext. Custom encryption schemes may vary in sophistication. Analysis and reverse engineering of malware samples may be enough to discover the algorithm and encryption key used. Some adversaries may also attempt to implement their own version of a well-known cryptographic algorithm instead of using a known implementation library, which may lead to unintentional errors. (Citation: F-Secure Cosmicduke)
Контрмеры |
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| Контрмера | Описание |
|---|---|
| Custom Cryptographic Protocol Mitigation |
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. Since the custom protocol used may not adhere to typical protocol standards, there may be opportunities to signature the traffic on a network level for detection. Signatures are often for unique indicators within protocols and may be based on the specific protocol used by a particular adversary or tool, and will likely be different across various malware families and versions. Adversaries will likely change tool C2 signatures over time or construct protocols in such a way as to avoid detection by common defensive tools. (Citation: University of Birmingham C2) |
| Network Intrusion Prevention |
Use intrusion detection signatures to block traffic at network boundaries. |
Обнаружение
If malware uses custom encryption with symmetric keys, it may be possible to obtain the algorithm and key from samples and use them to decode network traffic to detect malware communications signatures. (Citation: Fidelis DarkComet) 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 when communications do not follow the expected protocol behavior for the port that is being used. (Citation: University of Birmingham C2)
Ссылки
- Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.
- Fidelis Cybersecurity. (2015, August 4). Looking at the Sky for a DarkComet. Retrieved April 5, 2016.
- F-Secure Labs. (2014, July). COSMICDUKE Cosmu with a twist of MiniDuke. Retrieved July 3, 2014.
Связанные риски
Каталоги
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