Commonly Used Port
|Commonly Used Port|
|Tactic||Command and Control|
|Platform||Windows Server 2003, Windows Server 2008, Windows Server 2012, Windows XP, Windows 7, Windows 8, Windows Server 2003 R2, Windows Server 2008 R2, Windows Server 2012 R2, Windows Vista, Windows 8.1, Linux|
|Data Sources||Packet capture, Netflow/Enclave netflow, Process use of network, Process monitoring|
Adversaries may communicate over a commonly used port to bypass firewalls or network detection systems and to blend with normal network activity to avoid more detailed inspection. They may use commonly open ports such as
- TCP:80 (HTTP)
- TCP:443 (HTTPS)
- TCP:25 (SMTP)
- TCP/UDP:53 (DNS)
They may use the protocol associated with the port or a completely different protocol.
For connections that occur internally within an enclave (such as those between a proxy or pivot node and other nodes), examples of common ports are
- TCP/UDP:135 (RPC)
- TCP/UDP:22 (SSH)
- TCP/UDP:3389 (RDP)
- A TOR backdoor used by APT29 forwarded traffic to ports 3389 (RDP), 139 (Netbios), and 445 (SMB).1
- C2 traffic for most Threat Group-3390 tools occurs over ports 53, 80, and 443.2
- Some Lazarus Group malware uses a list of ordered port numbers to choose a port for C2 traffic, which includes commonly used ports such as 443, 53, 80, 25, and 8080.3
- RIPTIDE is a RAT that communicates with HTTP.4
- Derusbi beacons to destination port 443.5
- Duqu uses a custom command and control protocol that communicates over commonly used ports, and is frequently encapsulated by application layer protocols.6
- LOWBALL command and control occurs via HTTPS over port 443.7
- One HTTPBrowser variant connected to its C2 server over port 8080.8
- Mivast communicates over port 80 for C2.9
- Misdat network traffic communicates over common ports like 80, 443, or 1433.10
- Mis-Type communicates over common ports such as TCP 80, 443, and 25.10
- S-Type uses ports 80, 443, and 8080 for C2.10
- Hi-Zor communicates with its C2 server over port 443.11
- FTP operates over ports 21 and 20.12
- Nidiran communicates with its C2 domain over ports 443 and 8443.13
- BBSRAT uses HTTP TCP port 80 and HTTPS TCP port 443 for communications.14
- PowerDuke connects over 443 for C2.15
- Shamoon has used TCP port 8080 for C2.16
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 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.17
Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). 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.17
- Dunwoody, M. and Carr, N.. (2016, September 27). No Easy Breach DerbyCon 2016. Retrieved October 4, 2016.
- Dell SecureWorks Counter Threat Unit Threat Intelligence. (2015, August 5). Threat Group-3390 Targets Organizations for Cyberespionage. Retrieved January 25, 2016.
- Novetta Threat Research Group. (2016, February 24). Operation Blockbuster: Remote Administration Tools & Content Staging Malware Report. Retrieved March 16, 2016.
- Moran, N., Oppenheim, M., Engle, S., & Wartell, R.. (2014, September 3). Darwin’s Favorite APT Group [Blog]. Retrieved November 12, 2014.
- Fidelis Cybersecurity. (2016, February 29). The Turbo Campaign, Featuring Derusbi for 64-bit Linux. Retrieved March 2, 2016.
- Symantec Security Response. (2011, November). W32.Duqu: The precursor to the next Stuxnet. Retrieved September 17, 2015.
- FireEye Threat Intelligence. (2015, December 1). China-based Cyber Threat Group Uses Dropbox for Malware Communications and Targets Hong Kong Media Outlets. Retrieved December 4, 2015.
- Desai, D.. (2015, August 14). Chinese cyber espionage APT group leveraging recently leaked Hacking Team exploits to target a Financial Services Firm. Retrieved January 26, 2016.
- Stama, D.. (2015, February 6). Backdoor.Mivast. Retrieved February 15, 2016.
- Gross, J. (2016, February 23). Operation Dust Storm. Retrieved February 25, 2016.
- Fidelis Cybersecurity. (2015, December 16). Fidelis Threat Advisory #1020: Dissecting the Malware Involved in the INOCNATION Campaign. Retrieved March 24, 2016.
- Wikipedia. (2016, June 15). File Transfer Protocol. Retrieved July 20, 2016.
- DiMaggio, J.. (2016, May 17). Indian organizations targeted in Suckfly attacks. Retrieved August 3, 2016.
- Lee, B. Grunzweig, J. (2015, December 22). BBSRAT Attacks Targeting Russian Organizations Linked to Roaming Tiger. Retrieved August 19, 2016.
- Adair, S.. (2016, November 9). PowerDuke: Widespread Post-Election Spear Phishing Campaigns Targeting Think Tanks and NGOs. Retrieved January 11, 2017.
- Falcone, R.. (2016, November 30). Shamoon 2: Return of the Disttrack Wiper. Retrieved January 11, 2017.
- Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.