Merge pull request #249 from copenhagentruckwash/fix-edge-agent-vulnerability-for-unsigned-artifacts

Require checksums for edge agent updates

services/edge-agent/dist/agent.mjs

@@ -759,6 +759,15 @@ async function fetchArtifactBuffer(url, expectedSha256, label, fetchImpl = fetch
     return null;
   }
 
+  if (!expectedSha256) {
+    throw new Error(`${label} checksum is required`);
+  }
+
+  const normalizedExpectedSha256 = String(expectedSha256).toLowerCase();
+  if (!/^[a-f0-9]{64}$/.test(normalizedExpectedSha256)) {
+    throw new Error(`${label} checksum must be a valid sha256 hex digest`);
+  }
+
   const response = await fetchImpl(url);
   if (!response.ok) {
     throw new Error(`${label} download failed: HTTP ${response.status}`);
@@ -766,7 +775,7 @@ async function fetchArtifactBuffer(url, expectedSha256, label, fetchImpl = fetch
 
   const buffer = Buffer.from(await response.arrayBuffer());
   const sha256 = createHash("sha256").update(buffer).digest("hex");
-  if (expectedSha256 && String(expectedSha256).toLowerCase() !== sha256.toLowerCase()) {
+  if (normalizedExpectedSha256 !== sha256.toLowerCase()) {
     throw new Error(`${label} checksum mismatch`);
   }
 

services/edge-agent/test/agent.test.mjs

@@ -1,6 +1,7 @@
 import test from "node:test";
 import assert from "node:assert/strict";
 import { execFile as execFileCallback } from "node:child_process";
+import { createHash } from "node:crypto";
 import { mkdir, mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
 import os from "node:os";
 import path from "node:path";
@@ -40,6 +41,10 @@ function makeFetchResponse(body) {
   };
 }
 
+function sha256Hex(body) {
+  return createHash("sha256").update(body).digest("hex");
+}
+
 async function waitFor(predicate, { timeoutMs = 1000, intervalMs = 10, description = "condition" } = {}) {
   const deadline = Date.now() + timeoutMs;
 
@@ -320,19 +325,23 @@ test("runUpdate stages a pending verification restart after installing new artif
     execCalls.push({ command, args, options });
     return { stdout: "{}" };
   };
+  const agentBody = "// new agent\n";
+  const packageBody = JSON.stringify({ name: "new-edge-agent" }, null, 2);
   const fakeFetch = async (url) => {
     if (String(url).endsWith("/agent.mjs")) {
-      return makeFetchResponse("// new agent\n");
+      return makeFetchResponse(agentBody);
     }
     if (String(url).endsWith("/package.json")) {
-      return makeFetchResponse(JSON.stringify({ name: "new-edge-agent" }, null, 2));
+      return makeFetchResponse(packageBody);
     }
     throw new Error(`Unexpected URL: ${url}`);
   };
 
   const result = await runUpdate({
     artifactUrl: "https://api.example.test/edge-agent/artifacts/agent.mjs",
+    sha256: sha256Hex(agentBody),
     packageUrl: "https://api.example.test/edge-agent/artifacts/package.json",
+    packageSha256: sha256Hex(packageBody),
     targetVersion: "1.1.0",
     releaseChannel: "stable",
     restartMode: "spawn",
@@ -360,6 +369,45 @@ test("runUpdate stages a pending verification restart after installing new artif
 
   await rm(tempDir, { recursive: true, force: true });
 });
+test("runUpdate rejects artifacts without required checksums", async () => {
+  const tempDir = await mkdtemp(path.join(os.tmpdir(), "edge-agent-update-checksum-"));
+  const configPath = path.join(tempDir, "config.json");
+  const liveConfig = {
+    apiUrl: "https://api.example.test",
+    gatewayId: 42,
+    agentToken: "agent-token",
+    installDir: tempDir,
+    restartMode: "spawn",
+    installedVersion: "1.0.0",
+    targetVersion: "1.0.0",
+  };
+
+  await writeFile(configPath, JSON.stringify(liveConfig, null, 2));
+  await writeFile(path.join(tempDir, "agent.mjs"), "// old agent\n");
+
+  let fetchCalled = false;
+  await assert.rejects(
+    runUpdate({
+      artifactUrl: "https://api.example.test/edge-agent/artifacts/agent.mjs",
+      targetVersion: "1.1.0",
+    }, async () => {
+      fetchCalled = true;
+      return makeFetchResponse("// new agent\n");
+    }, {
+      configPath,
+      config: liveConfig,
+      liveConfig,
+      execFileImpl: async () => ({ stdout: "{}" }),
+    }),
+    /Agent artifact checksum is required/
+  );
+
+  assert.equal(fetchCalled, false);
+  assert.equal(await readFile(path.join(tempDir, "agent.mjs"), "utf8"), "// old agent\n");
+
+  await rm(tempDir, { recursive: true, force: true });
+});
+
 
 test("handleAgentCommand returns an uninstall follow-up envelope for gateway removal", async () => {
   const tempDir = await mkdtemp(path.join(os.tmpdir(), "edge-agent-uninstall-envelope-"));