Fig. 1 – A screenshot showing the results of Get-InjectedThreadEx scanning a process into which a 4.11 Beacon has just been injected.
Cobalt Strike 4.11 has been unveiled, featuring groundbreaking evasion capabilities and network stealth enhancements that redefine red team operations. This release introduces three revolutionary features alongside significant quality-of-life improvements.
Next-Generation Evasion Framework
- Smart Sleepmask: Automatically obfuscates Beacon memory, heap allocations, and itself during sleep cycles. Developers note: “The new evasive Sleepmask makes Beacon robust against static signatures at runtime, out-of-the-box”
- ObfSetThreadContext Injection: Novel process injection technique that mimics legitimate thread behavior. Early testing shows 100% evasion against Get-InjectedThreadEx scans
- Transform-Obfuscate: Multi-layer payload obfuscation supporting LZNT1 compression, RC4 encryption, XOR encoding, and Base64 transformations
“With transform-obfuscate, we’re bringing Malleable C2-style customization to payload structure itself. Users can now emulate advanced malware like Roshtyak with 14+ transformation layers.”
Asynchronous BOF Execution
The new async-execute.dll enables parallel BOF execution without blocking Beacon operations. Key features:
- Background job server mode for continuous operation
- Integrated indirect syscall support
- Automatic memory cleanup
Cobalt Strike 4.11: Shhhhhh, Beacon is Sleeping….
DNS Over HTTPS Beacon
The new DoH implementation blends DNS C2 with legitimate web traffic:
dns-beacon "STEALTH_DOH" {
set comm_mode "dns-over-https";
set doh_verb "GET";
set doh_server "cloudflare-dns.com";
header "Content-Type" "application/dns-message";
}Default configuration uses Cloudflare infrastructure, with options for custom proxies and header manipulation.
Quality of Life Enhancements
- Beacon console variables ($BEACON_PID, $BEACON_ARCH)
- Reorganized help command with custom grouping
- Enhanced syscall resolution for BeaconGate development
- GUI improvements including console buffer customization
“The postex kit demonstrates our commitment to user empowerment. With UDRL-VS and Sleepmask-VS, customers have the same toolchain we use internally.”
Key Considerations
- Legacy stomp loader deprecated in 4.12
- DoH requires preconfigured DNS infrastructure
- Transform operations may increase payload generation time
Cobalt Strike continues to push the boundaries of adversarial simulation, with 4.11 delivering 23 documented improvements across its evasion stack, post-exploitation workflow, and operator experience. The complete release notes can be found on the official portal.
