Proxy: Multi-hop 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 |
To disguise the source of malicious traffic, adversaries may chain together multiple proxies. Typically, a defender will be able to identify the last proxy traffic traversed before it enters their network; the defender may or may not be able to identify any previous proxies before the last-hop proxy. This technique makes identifying the original source of the malicious traffic even more difficult by requiring the defender to trace malicious traffic through several proxies to identify its source.
Procedure Examples
| Name | Description |
|---|---|
| APT29 |
A backdoor used by APT29 created a Tor hidden service to forward traffic from the Tor client to local ports 3389 (RDP), 139 (Netbios), and 445 (SMB) enabling full remote access from outside the network.[9] |
| Attor | |
| Dok | |
| FIN4 | |
| GreyEnergy |
GreyEnergy has used Tor relays for Command and Control servers.[3] |
| Inception |
Inception used chains of compromised routers to proxy C2 communications between them and cloud service providers.[11] |
| Keydnap |
Keydnap uses a copy of tor2web proxy for HTTPS communications.[4] |
| MacSpy | |
| Tor |
Traffic traversing the Tor network will be forwarded to multiple nodes before exiting the Tor network and continuing on to its intended destination.[1] |
| Ursnif | |
| WannaCry |
Mitigations
| Mitigation | Description |
|---|---|
| Filter Network Traffic |
Traffic to known anonymity networks and C2 infrastructure can be blocked through the use of network allow and block lists. It should be noted that this kind of blocking may be circumvented by other techniques like Domain Fronting. |
Detection
When observing use of Multi-hop proxies, network data from the actual command and control servers could allow correlating incoming and outgoing flows to trace malicious traffic back to its source. Multi-hop proxies can also be detected by alerting on traffic to known anonymity networks (such as Tor) or known adversary infrastructure that uses this technique.
References
- Roger Dingledine, Nick Mathewson and Paul Syverson. (2004). Tor: The Second-Generation Onion Router. Retrieved December 21, 2017.
- Patrick Wardle. (n.d.). Mac Malware of 2017. Retrieved September 21, 2018.
- Cherepanov, A. (2018, October). GREYENERGY A successor to BlackEnergy. Retrieved November 15, 2018.
- Patrick Wardle. (2017, January 1). Mac Malware of 2016. Retrieved September 21, 2018.
- Counter Threat Unit Research Team. (2017, May 18). WCry Ransomware Analysis. Retrieved March 26, 2019.
- NJCCIC. (2016, September 27). Ursnif. Retrieved June 4, 2019.
- Proofpoint Staff. (2016, August 25). Nightmare on Tor Street: Ursnif variant Dreambot adds Tor functionality. Retrieved June 5, 2019.
- Hromcova, Z. (2019, October). AT COMMANDS, TOR-BASED COMMUNICATIONS: MEET ATTOR, A FANTASY CREATURE AND ALSO A SPY PLATFORM. Retrieved May 6, 2020.
- Dunwoody, M. and Carr, N.. (2016, September 27). No Easy Breach DerbyCon 2016. Retrieved October 4, 2016.
- Vengerik, B. et al.. (2014, December 5). Hacking the Street? FIN4 Likely Playing the Market. Retrieved December 17, 2018.
- Symantec. (2018, March 14). Inception Framework: Alive and Well, and Hiding Behind Proxies. Retrieved May 8, 2020.