Formal Verification and Immune Patching for Operating System Command Injection
A service passes a filename or network address into a system shell, allowing an attacker to append a semicolon and run arbitrary server commands. The wire filter blocks destructive shell commands before transmission, confirms the flaw with a deterministic echo token, and compiles a strict shell-metacharacter filter.
Operating system command injection appears when an application invokes a system shell to run diagnostic utilities, archive tools, or document converters with unsanitized user arguments. In autonomous tool-calling workflows, a single unquoted shell separator lets an external caller execute arbitrary binaries under the service account.
1. Interception and Rule Synthesis Schematic for INJ-CMD
Verification sequence for INJ-CMD: candidate probe inspection by wire rule SEC-ZD-CMD-01, differential confirmation via witness e22a45273df881ef, and compilation of gateway contract IMMUNE-CMD-E22A4527.
2. In-Path Mutation Blocking and Paired Decoy Verification (INJ-CMD)
Before any test request leaves the verifier, the in-path software filter parses the candidate string against destructive shell patterns. Commands attempting recursive file deletion, disk formatting, process termination, or privilege escalation are intercepted by rule SEC-ZD-CMD-01 prior to socket transmission.
The verifier proves shell execution by comparing a deterministic token reflection against a hardened endpoint that uses argument arrays without a shell interpreter. Across four benchmark scenarios on the local testbed, the engine records two true positives, zero false positives, two true negatives, and zero false negatives.
Class Identifier: INJ-CMD (command_injection)
Execution Mode: Active Safe Probing (AUTO_SCAN)
Candidate Probe: POST /api/v1/vuln/cmdi/ping {"host": "127.0.0.1; id"}
Blocked Mutation: rm -rf /; mkfs.ext4 /dev/sda; shutdown -h now
Stand Confusion Matrix: TP = 2, FP = 0, TN = 2, FN = 0 (FPR = 0.0%)
Wire Sandbox Rule: SEC-ZD-CMD-01
Formal Witness Hash: e22a45273df881ef
Compiled Sentinel Rule: IMMUNE-CMD-E22A4527 (synthesis time 20 µs)3. Automatic Synthesis of Gateway Rule IMMUNE-CMD-E22A4527
From the verified witness e22a45273df881ef, the compiler generates rule IMMUNE-CMD-E22A4527 in 20 microseconds. The compiled rule blocks command separators, subshell expansions, and pipeline operators in mcp-sentinel while preserving valid hostnames and file identifiers.
4. Related Benchmark Classes on the INDRA Stand
INJ-SQL: Database Query InjectionDIR-TRV: Filesystem Path TraversalAUTH-BOLA: Broken Object Level AuthorizationSSRF-INT: Server-Side Request Forgery and Redirect BypassSEC-LEAK: Authentication Token and Secret ExposureHDR-SEC: Missing Transport and Framing Security HeadersDOS-RSRC: Computational Resource Exhaustion (Isolated Lab Mode)