Sub-technique of T1573 Encrypted Channel.View on attack.mitre.org
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, many 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.
Rules on DetectionCode tagged with T1573.002.
| Rule | Type | Risk | Data source |
|---|---|---|---|
| Cisco Secure Firewall - Blacklisted SSL Certificate Fingerprint | TTP | NULL | Cisco Secure Firewall Threat Defense Connection Event |
| Cisco Secure Firewall - High EVE Threat Confidence | Anomaly | NULL | Cisco Secure Firewall Threat Defense Connection Event |
| Cisco Secure Firewall - Intrusion Events by Threat Activity | Anomaly | NULL | Cisco Secure Firewall Threat Defense Intrusion Event |
| Cisco Secure Firewall - Lumma Stealer Download Attempt | Anomaly | NULL | Cisco Secure Firewall Threat Defense Intrusion Event |
| Cisco Secure Firewall - Lumma Stealer Outbound Connection Attempt | Anomaly | NULL | Cisco Secure Firewall Threat Defense Intrusion Event |
| Used by | Procedure example |
|---|---|
| GroupAPT42 | APT42 has used tools such as NICECURL with command and control communication taking place over HTTPS. |
| GroupCobalt Group | Cobalt Group has used the Plink utility to create SSH tunnels. |
| GroupFIN6 | FIN6 used the Plink command-line utility to create SSH tunnels to C2 servers. |
| GroupFIN8 | FIN8 has used the Plink utility to tunnel RDP back to C2 infrastructure. |
| GroupMedusa Group | Medusa Group has used HTTPS for command and control. |
| GroupOilRig | OilRig used the PowerExchange utility and other tools to create tunnels to C2 servers. |
| GroupRedCurl | RedCurl has used HTTPS for C2 communication. |
| GroupRedEcho | RedEcho uses SSL for network communication. |
| Used by | Procedure example |
|---|---|
| Malwareadbupd | adbupd contains a copy of the OpenSSL library to encrypt C2 traffic. |
| MalwareADVSTORESHELL | A variant of ADVSTORESHELL encrypts some C2 with RSA. |
| MalwareAttor | Attor's Blowfish key is encrypted with a public RSA key. |
| MalwareBADHATCH | BADHATCH can beacon to a hardcoded C2 IP address using TLS encryption every 5 minutes. |
| MalwareBazar | Bazar can use TLS in C2 communications. |
| MalwareBISCUIT | BISCUIT uses SSL for encrypting C2 communications. |
| MalwareBOLDMOVE | BOLDMOVE uses the WolfSSL library to implement SSL encryption for command and control communication. |
| MalwareBRICKSTORM | BRICKSTORM has communicated with C2 infrastructure via TLS. |
| Used by | Procedure example |
|---|---|
| CampaignAPT41 DUST | APT41 DUST used HTTPS for command and control. |
| CampaignC0021 | During C0021, the threat actors used SSL via TCP port 443 for C2 communications. |
| CampaignIndian Critical Infrastructure Intrusions | During Indian Critical Infrastructure Intrusions, RedEcho used SSL for network communication. |
| CampaignOperation Wocao | During Operation Wocao, threat actors' proxy implementation "Agent" upgraded the socket in use to a TLS socket. |
| CampaignVersa Director Zero Day Exploitation | Versa Director Zero Day Exploitation used HTTPS for command and control of compromised Versa Director servers. |
Data from MITRE ATT&CK® (Enterprise). ATT&CK® is a registered trademark of The MITRE Corporation.
