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T1048.002 Exfiltration Over Asymmetric Encrypted Non-C2 Protocol

Adversaries may steal data by exfiltrating it over an asymmetrically encrypted network protocol other than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.

Asymmetric encryption algorithms are those that use different keys on each end of the channel. Also known as public-key cryptography, this requires pairs of cryptographic keys that can encrypt/decrypt data from the corresponding key. Each end of the communication channels requires a private key (only in the procession of that entity) and the public key of the other entity. The public keys of each entity are exchanged before encrypted communications begin.

Network protocols that use asymmetric encryption (such as HTTPS/TLS/SSL) often utilize symmetric encryption once keys are exchanged. Adversaries may opt to use these encrypted mechanisms that are baked into a protocol.

Item Value
ID T1048.002
Sub-techniques T1048.001, T1048.002, T1048.003
Tactics TA0010
Platforms Linux, Windows, macOS
Version 1.1
Created 15 March 2020
Last Modified 15 October 2021

Procedure Examples

ID Name Description
G0007 APT28 APT28 has exfiltrated archives of collected data previously staged on a target’s OWA server via HTTPS.4
S1040 Rclone Rclone can exfiltrate data over SFTP or HTTPS via WebDAV.3
C0024 SolarWinds Compromise During the SolarWinds Compromise, APT29 exfiltrated collected data over a simple HTTPS request to a password-protected archive staged on a victim’s OWA servers.5

Mitigations

ID Mitigation Description
M1057 Data Loss Prevention Data loss prevention can detect and block sensitive data being uploaded via web browsers.
M1037 Filter Network Traffic Enforce proxies and use dedicated servers for services such as DNS and only allow those systems to communicate over respective ports/protocols, instead of all systems within a network.
M1031 Network Intrusion Prevention Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary command and control infrastructure and malware can be used to mitigate activity at the network level.
M1030 Network Segmentation Follow best practices for network firewall configurations to allow only necessary ports and traffic to enter and exit the network.2

Detection

ID Data Source Data Component
DS0017 Command Command Execution
DS0022 File File Access
DS0029 Network Traffic Network Connection Creation

References

  1. Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016. ↩

  2. Microsoft. (2004, February 6). Perimeter Firewall Design. Retrieved April 25, 2016. ↩

  3. Nick Craig-Wood. (n.d.). Rclone syncs your files to cloud storage. Retrieved August 30, 2022. ↩

  4. NSA, CISA, FBI, NCSC. (2021, July). Russian GRU Conducting Global Brute Force Campaign to Compromise Enterprise and Cloud Environments. Retrieved July 26, 2021. ↩

  5. Cash, D. et al. (2020, December 14). Dark Halo Leverages SolarWinds Compromise to Breach Organizations. Retrieved December 29, 2020. ↩