Proxy: Internal Proxy
Other sub-techniques of Proxy (4)
| ID | Name |
|---|---|
| T1090.001 | Internal Proxy |
| T1090.002 | External Proxy |
| T1090.003 | Multi-hop Proxy |
| T1090.004 | Domain Fronting |
Adversaries may use an internal proxy to direct command and control traffic between two or more systems in a compromised environment. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap. [1] Adversaries use internal proxies to manage command and control communications inside a compromised environment, to reduce the number of simultaneous outbound network connections, to provide resiliency in the face of connection loss, or to ride over existing trusted communications paths between infected systems to avoid suspicion. Internal proxy connections may use common peer-to-peer (p2p) networking protocols, such as SMB, to better blend in with the environment.
By using a compromised internal system as a proxy, adversaries may conceal the true destination of C2 traffic while reducing the need for numerous connections to external systems.
Procedure Examples
| Name | Description |
|---|---|
| APT39 |
APT39 used custom tools to create SOCK5 and custom protocol proxies between infected hosts. [2][3] |
| BACKSPACE |
The "ZJ" variant of BACKSPACE allows "ZJ link" infections with Internet access to relay traffic from "ZJ listen" to a command server.[4] |
| CHOPSTICK |
CHOPSTICK used a proxy server between victims and the C2 server.[5] |
| Cobalt Strike |
Cobalt Strike can be configured to have commands relayed over a peer-to-peer network of infected hosts. This can be used to limit the number of egress points, or provide access to a host without direct internet access.[6] |
| Drovorub |
Drovorub can use a port forwarding rule on its agent module to relay network traffic through the client module to a remote host on the same network.[7] |
| Duqu |
Duqu can be configured to have commands relayed over a peer-to-peer network of infected hosts if some of the hosts do not have Internet access.[8] |
| FatDuke |
FatDuke can used pipes to connect machines with restricted internet access to remote machines via other infected hosts.[9] |
| Hikit | |
| InvisiMole |
InvisiMole can function as a proxy to create a server that relays communication between the client and C&C server, or between two clients.[11] |
| MiniDuke |
MiniDuke can can use a named pipe to forward communications from one compromised machine with internet access to other compromised machines.[9] |
| Strider |
Strider has used local servers with both local network and Internet access to act as internal proxy nodes to exfiltrate data from other parts of the network without direct Internet access.[12] |
| UNC2452 |
UNC2452 configured at least one instance of Cobalt Strike to use a network pipe over SMB during the 2020 SolarWinds intrusion.[13] |
Mitigations
| Mitigation | Description |
|---|---|
| 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. Signatures are often for unique indicators within protocols and may be based on the specific C2 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.[14] |
Detection
Analyze network data for uncommon data flows between clients that should not or often do not communicate with one another. 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.[14]
References
- Wilhoit, K. (2013, March 4). In-Depth Look: APT Attack Tools of the Trade. Retrieved December 2, 2015.
- Hawley et al. (2019, January 29). APT39: An Iranian Cyber Espionage Group Focused on Personal Information. Retrieved February 19, 2019.
- Rusu, B. (2020, May 21). Iranian Chafer APT Targeted Air Transportation and Government in Kuwait and Saudi Arabia. Retrieved May 22, 2020.
- FireEye Labs. (2015, April). APT30 AND THE MECHANICS OF A LONG-RUNNING CYBER ESPIONAGE OPERATION. Retrieved May 1, 2015.
- ESET. (2016, October). En Route with Sednit - Part 2: Observing the Comings and Goings. Retrieved November 21, 2016.
- Strategic Cyber LLC. (2017, March 14). Cobalt Strike Manual. Retrieved May 24, 2017.
- NSA/FBI. (2020, August). Russian GRU 85th GTsSS Deploys Previously Undisclosed Drovorub Malware. Retrieved August 25, 2020.
- Symantec Security Response. (2011, November). W32.Duqu: The precursor to the next Stuxnet. Retrieved September 17, 2015.
- Faou, M., Tartare, M., Dupuy, T. (2019, October). OPERATION GHOST. Retrieved September 23, 2020.
- Novetta. (n.d.). Operation SMN: Axiom Threat Actor Group Report. Retrieved November 12, 2014.
- Hromcová, Z. (2018, June 07). InvisiMole: Surprisingly equipped spyware, undercover since 2013. Retrieved July 10, 2018.
- Kaspersky Lab's Global Research & Analysis Team. (2016, August 8). ProjectSauron: top level cyber-espionage platform covertly extracts encrypted government comms. Retrieved August 17, 2016.
- Symantec Threat Hunter Team. (2021, January 18). Raindrop: New Malware Discovered in SolarWinds Investigation. Retrieved January 19, 2021.
- Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.