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.
View in MITRE ATT&CK®| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| AC-4 | Information Flow Enforcement | Protects | T1573.002 | Asymmetric Cryptography | |
| CA-7 | Continuous Monitoring | Protects | T1573.002 | Asymmetric Cryptography | |
| CM-2 | Baseline Configuration | Protects | T1573.002 | Asymmetric Cryptography | |
| CM-6 | Configuration Settings | Protects | T1573.002 | Asymmetric Cryptography | |
| CM-7 | Least Functionality | Protects | T1573.002 | Asymmetric Cryptography | |
| SC-12 | Cryptographic Key Establishment and Management | Protects | T1573.002 | Asymmetric Cryptography | |
| SC-16 | Transmission of Security and Privacy Attributes | Protects | T1573.002 | Asymmetric Cryptography | |
| SC-23 | Session Authenticity | Protects | T1573.002 | Asymmetric Cryptography | |
| SC-7 | Boundary Protection | Protects | T1573.002 | Asymmetric Cryptography | |
| SI-3 | Malicious Code Protection | Protects | T1573.002 | Asymmetric Cryptography | |
| SI-4 | System Monitoring | Protects | T1573.002 | Asymmetric Cryptography | |
| azure_sentinel | Azure Sentinel | technique_scores | T1573.002 | Asymmetric Cryptography |
Comments
The following Azure Sentinel Analytics queries can detect potentially malicious usage of asymmetric cryptography channels: "DNS events related to ToR proxies" can identify potential use of Tor, though it provides only minimal coverage because it only covers a set of common domains and is easily bypassed via hardcoded IP addresses, redirection, etc. "Powershell Empire cmdlets seen in command line" can identify use of Empire, which can use TLS to encrypt a command and control channel.
References
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