🛡️ Sentinel: [CRITICAL] Fix command validation bypass

.jules/sentinel.md

@@ -17,3 +17,7 @@
 **Vulnerability:** The `verify_github_sig` function in `apps/server/src/infra_routes.rs` verified GitHub webhook signatures using standard string comparison `expected.eq_ignore_ascii_case(hex_sig)`.
 **Learning:** String comparison functions exit early as soon as a character mismatch is found. In a cryptographic context, this variable response time leaks information and allows an attacker to perform a timing attack to forge a valid HMAC signature by guessing it byte by byte.
 **Prevention:** Always use a constant-time comparison library (like `hmac`'s `verify_slice()`) to compare cryptographic hashes, secrets, and signatures to prevent side-channel timing attacks. Avoid custom implementations of standard cryptographic algorithms.
+## 2024-05-18 - Exact Token Matching in Command Validation
+**Vulnerability:** Command validation in `workdir_cmd.rs` relied on joined strings for multi-word blocked phrases (e.g., `rm `), which allowed an attacker to bypass it by placing the sensitive token at the end of the command string (e.g., `npm run rm`).
+**Learning:** Checking a joined string for an exact blocked token padding (like `rm `) is insufficient as it fails to catch exact matches that appear as the last argument where no trailing space exists. Relying solely on tokenized matches also breaks multi-word blocked phrases. Both checks must be implemented simultaneously for robustness.
+**Prevention:** Always verify both the joined command string against multi-word blocked phrases AND individual tokenized arguments for exact matches of sensitive binaries.

crates/agent/src/tools/workdir_cmd.rs

@@ -112,6 +112,20 @@ fn validate_command(raw: &str) -> std::result::Result<Vec<String>, String> {
             return Err(format!("token interdit dans la commande : {bad}"));
         }
     }
+    for part in &parts {
+        let p_lower = part.to_ascii_lowercase();
+        if p_lower == "rm"
+            || p_lower == "sudo"
+            || p_lower == "chmod"
+            || p_lower == "chown"
+            || p_lower == "curl"
+            || p_lower == "wget"
+            || p_lower == "ssh"
+            || p_lower == "scp"
+        {
+            return Err(format!("token exact interdit dans la commande : {}", part));
+        }
+    }
     let bin = parts[0].as_str();
     let bin_base = Path::new(bin)
         .file_name()
@@ -354,6 +368,7 @@ mod tests {
     fn blocks_obfuscated_commands() {
         assert!(validate_command("npm run \"s\"udo").is_err());
         assert!(validate_command("cat \"..\"/\"..\"/etc/passwd").is_err());
+        assert!(validate_command("npm run rm").is_err());
     }
 }