Egress Validation (NET-EGRESS)

Validate that the secure sandbox enforces a default-deny posture for network egress and prevents proxy bypass attempts.

Objectives

• Enforce egressDefaultAction: "deny".
• Require proxy routing for all outbound traffic.
• Ensure fail-closed behavior during proxy outages.
• Prevent applications from bypassing proxy settings.
• Maintain IPv4 and IPv6 parity for egress controls.

Controls Under Test

• runtime.networking.egressDefaultAction
• Proxy enforcement and pinning
• Network namespace firewall

Test Scenarios

ID	Threat / Scenario	Universal Procedure	Expected Outcome & Audit
NET-EGRESS-01	Direct IP Access	Adversary attempts to bypass DNS filters. Initiate an HTTP request to a specific public IP (e.g., 1.1.1.1) using a timeout flag (e.g., curl -v --connect-timeout 5 <IP>).	Pass: Connection timeout or refused. No HTTP 200/301. Audit: action: deny, protocol: tcp
NET-EGRESS-02	Unauthorized Proxy Usage	Adversary attempts to use a non-designated proxy. Configure a user-defined proxy (e.g., export https_proxy=attacker.com:8080) and attempt a connection.	Pass: Connection failed; traffic must traverse the designated gateway. Audit: action: deny, reason: unauthorizedProxy
NET-EGRESS-03	Direct UDP Egress	Exfiltration via non-TCP protocols. Attempt to send UDP packets to an external destination (e.g., nc -u <IP> 53 or 123).	Pass: Packets dropped. Audit: action: deny, protocol: udp
NET-EGRESS-04	ICMP Egress	Network mapping or tunneling via ICMP. Attempt to ping an external host (e.g., ping 8.8.8.8).	Pass: Request timed out / Destination unreachable. Audit: action: deny, protocol: icmp
NET-EGRESS-05	Environment Proxy Variables / Client Flags	Attempt to bypass designated proxies using http_proxy/https_proxy/all_proxy or client --proxy flags to an unauthorized endpoint. Example: export HTTPS_PROXY=http://attacker:8080 && curl -v https://example.com.	Pass: Denied; only designated proxies are accepted. Audit: category: network, action: deny, reason: unauthorizedProxy, proxyEnforced: true
NET-EGRESS-06	NO_PROXY / --noproxy Bypass	Disable proxy routing via environment or client flags. Example: export NO_PROXY=* && curl -v https://example.com or curl --noproxy "*" https://example.com.	Pass: Denied; proxy bypass refused. Audit: action: deny, reason: proxyBypassAttempt, proxyEnforced: true
NET-EGRESS-07	Proxy Bypass	Proxy bypass via noproxy or tunnels. Attempt connection bypassing proxy settings (e.g., curl --noproxy "*") or using HTTP CONNECT to arbitrary ports.	Pass: Connection failed; cannot bypass enforced proxy. Audit: reason: proxyBypassAttempt.
NET-EGRESS-08	PAC/WPAD Hijack	Present a malicious PAC file or enable WPAD to route via a non-designated proxy; attempt outbound HTTPS.	Pass: Denied/ignored; only designated proxies are accepted. Audit: action: deny, reason: pacNotTrusted or wpadBlocked, proxyEnforced: true
NET-EGRESS-09	Proxy Fail-Closed	Simulate designated proxy outage (stop service or blackhole IP) and attempt outbound HTTPS.	Pass: Connection denied; no direct fallback. Audit: action: deny, reason: proxyUnavailable, proxyEnforced: true
NET-EGRESS-10	Designated Proxy Identity/Pinning	Intercept proxy TLS or present a non-pinned CA/cert to the client; attempt CONNECT/HTTPS.	Pass: TLS handshake fails; no fallback to direct. Audit: action: deny, reason: certMismatch or pinningFailed, proxyEnforced: true
NET-EGRESS-11	IPv6 Direct Egress	Attempt IPv6 literal or AAAA target to bypass IPv4 rules. Example: curl -6 -v https://[2606:4700:4700::1111]/.	Pass: Denied; parity with IPv4 posture. Audit: action: deny, protocol: tcp, ipVersion: 6
NET-EGRESS-12	CONNECT Tunneling to Non-Proxy	Use HTTP CONNECT to an endpoint that is not an approved proxy. Example: curl -v -x https://nonproxy.example:443 https://target.example.	Pass: Denied; only designated proxies are valid CONNECT targets. Audit: action: deny, reason: destNotProxy, proxyEnforced: true
NET-EGRESS-13	Runtime Proxy Ignorance	Direct socket connection bypassing proxy settings. Execute a binary/script that ignores system proxy env vars and opens a direct TCP socket.	Pass: Blocked by firewall/namespace. Audit: action: deny, protocol: tcp

Evidence Requirements

• Audit category: network
• Golden fields: category, action, rule.id, integrity.hash
• Required fields for these tests: protocol, destination, reason, proxyEnforced
• Conditional fields (when applicable): alpn, sni, ipVersion, proxyRef