fix(security): harden project settings trust boundary + MCP sanitization

- Sanitize MCP tool result text with recursivelySanitizeUnicode() to prevent
  Unicode injection via malicious MCP servers (tool definitions and prompts
  were already sanitized, but tool call results were not)
- Read sandbox.enabled only from trusted settings sources (user, local, flag,
  policy) — exclude projectSettings to prevent malicious repos from silently
  disabling the sandbox via .claude/settings.json
- Disable git hooks in plugin marketplace clone/pull/submodule operations
  with core.hooksPath=/dev/null to prevent code execution from cloned repos
- Remove ANTHROPIC_FOUNDRY_API_KEY from SAFE_ENV_VARS to prevent credential
  injection from project-scoped settings without trust verification
- Add ssrfGuardedLookup to WebFetch HTTP requests to block DNS rebinding
  attacks that could reach cloud metadata or internal services

Security: closes trust boundary gap where project settings could override
security-critical configuration. Follows the existing pattern established
by hasAllowBypassPermissionsMode() which already excludes projectSettings.

Co-authored-by: auriti <auriti@users.noreply.github.com>

src/__tests__/security-hardening.test.ts

@@ -0,0 +1,126 @@
+/**
+ * Security hardening regression tests.
+ *
+ * Covers:
+ * 1. MCP tool result Unicode sanitization
+ * 2. Sandbox settings source filtering (exclude projectSettings)
+ * 3. Plugin git clone/pull hooks disabled
+ * 4. ANTHROPIC_FOUNDRY_API_KEY removed from SAFE_ENV_VARS
+ * 5. WebFetch SSRF protection via ssrfGuardedLookup
+ */
+
+import { describe, test, expect } from 'bun:test'
+import { resolve } from 'path'
+
+const SRC = resolve(import.meta.dir, '..')
+const file = (relative: string) => Bun.file(resolve(SRC, relative))
+
+// ---------------------------------------------------------------------------
+// Fix 1: MCP tool result Unicode sanitization
+// ---------------------------------------------------------------------------
+describe('MCP tool result sanitization', () => {
+  test('transformResultContent sanitizes text content', async () => {
+    const content = await file('services/mcp/client.ts').text()
+    // Tool definitions are already sanitized (line ~1798)
+    expect(content).toContain('recursivelySanitizeUnicode(result.tools)')
+    // Tool results must also be sanitized
+    expect(content).toMatch(
+      /case 'text':[\s\S]*?recursivelySanitizeUnicode\(resultContent\.text\)/,
+    )
+  })
+
+  test('resource text content is also sanitized', async () => {
+    const content = await file('services/mcp/client.ts').text()
+    expect(content).toMatch(
+      /recursivelySanitizeUnicode\(\s*`\$\{prefix\}\$\{resource\.text\}`/,
+    )
+  })
+})
+
+// ---------------------------------------------------------------------------
+// Fix 2: Sandbox settings source filtering
+// ---------------------------------------------------------------------------
+describe('Sandbox settings trust boundary', () => {
+  test('getSandboxEnabledSetting does not use getSettings_DEPRECATED', async () => {
+    const content = await file('utils/sandbox/sandbox-adapter.ts').text()
+    // Extract the getSandboxEnabledSetting function body
+    const fnMatch = content.match(
+      /function getSandboxEnabledSetting\(\)[^{]*\{([\s\S]*?)\n\}/,
+    )
+    expect(fnMatch).not.toBeNull()
+    const fnBody = fnMatch![1]
+    // Must NOT use getSettings_DEPRECATED (reads all sources including project)
+    expect(fnBody).not.toContain('getSettings_DEPRECATED')
+    // Must use getSettingsForSource for individual trusted sources
+    expect(fnBody).toContain("getSettingsForSource('userSettings')")
+    expect(fnBody).toContain("getSettingsForSource('policySettings')")
+    // Must NOT read from projectSettings
+    expect(fnBody).not.toContain("'projectSettings'")
+  })
+})
+
+// ---------------------------------------------------------------------------
+// Fix 3: Plugin git hooks disabled
+// ---------------------------------------------------------------------------
+describe('Plugin git operations disable hooks', () => {
+  test('gitClone includes core.hooksPath=/dev/null', async () => {
+    const content = await file('utils/plugins/marketplaceManager.ts').text()
+    // The clone args must disable hooks
+    const cloneSection = content.slice(
+      content.indexOf('export async function gitClone('),
+      content.indexOf('export async function gitClone(') + 2000,
+    )
+    expect(cloneSection).toContain("'core.hooksPath=/dev/null'")
+  })
+
+  test('gitPull includes core.hooksPath=/dev/null', async () => {
+    const content = await file('utils/plugins/marketplaceManager.ts').text()
+    const pullSection = content.slice(
+      content.indexOf('export async function gitPull('),
+      content.indexOf('export async function gitPull(') + 2000,
+    )
+    expect(pullSection).toContain("'core.hooksPath=/dev/null'")
+  })
+
+  test('gitSubmoduleUpdate includes core.hooksPath=/dev/null', async () => {
+    const content = await file('utils/plugins/marketplaceManager.ts').text()
+    const subSection = content.slice(
+      content.indexOf('async function gitSubmoduleUpdate('),
+      content.indexOf('async function gitSubmoduleUpdate(') + 1000,
+    )
+    expect(subSection).toContain("'core.hooksPath=/dev/null'")
+  })
+})
+
+// ---------------------------------------------------------------------------
+// Fix 4: ANTHROPIC_FOUNDRY_API_KEY not in SAFE_ENV_VARS
+// ---------------------------------------------------------------------------
+describe('SAFE_ENV_VARS excludes credentials', () => {
+  test('ANTHROPIC_FOUNDRY_API_KEY is not in SAFE_ENV_VARS', async () => {
+    const content = await file('utils/managedEnvConstants.ts').text()
+    // Extract the SAFE_ENV_VARS set definition
+    const safeStart = content.indexOf('export const SAFE_ENV_VARS')
+    const safeEnd = content.indexOf('])', safeStart)
+    const safeSection = content.slice(safeStart, safeEnd)
+    expect(safeSection).not.toContain('ANTHROPIC_FOUNDRY_API_KEY')
+  })
+})
+
+// ---------------------------------------------------------------------------
+// Fix 5: WebFetch SSRF protection
+// ---------------------------------------------------------------------------
+describe('WebFetch SSRF guard', () => {
+  test('getWithPermittedRedirects uses ssrfGuardedLookup', async () => {
+    const content = await file('tools/WebFetchTool/utils.ts').text()
+    expect(content).toContain(
+      "import { ssrfGuardedLookup } from '../../utils/hooks/ssrfGuard.js'",
+    )
+    // The axios.get call in getWithPermittedRedirects must include lookup
+    const fnSection = content.slice(
+      content.indexOf('export async function getWithPermittedRedirects('),
+      content.indexOf('export async function getWithPermittedRedirects(') +
+        1000,
+    )
+    expect(fnSection).toContain('lookup: ssrfGuardedLookup')
+  })
+})

src/services/mcp/client.ts

@@ -2524,7 +2524,7 @@ export async function transformResultContent(
       return [
         {
           type: 'text',
-          text: resultContent.text,
+          text: recursivelySanitizeUnicode(resultContent.text) as string,
         },
       ]
     case 'audio': {
@@ -2569,7 +2569,9 @@ export async function transformResultContent(
         return [
           {
             type: 'text',
-            text: `${prefix}${resource.text}`,
+            text: recursivelySanitizeUnicode(
+              `${prefix}${resource.text}`,
+            ) as string,
           },
         ]
       } else if ('blob' in resource) {

src/tools/WebFetchTool/utils.ts

@@ -15,6 +15,7 @@ import {
 } from '../../utils/mcpOutputStorage.js'
 import { getSettings_DEPRECATED } from '../../utils/settings/settings.js'
 import { asSystemPrompt } from '../../utils/systemPromptType.js'
+import { ssrfGuardedLookup } from '../../utils/hooks/ssrfGuard.js'
 import { isPreapprovedHost } from './preapproved.js'
 import { makeSecondaryModelPrompt } from './prompt.js'
 
@@ -281,6 +282,7 @@ export async function getWithPermittedRedirects(
       maxRedirects: 0,
       responseType: 'arraybuffer',
       maxContentLength: MAX_HTTP_CONTENT_LENGTH,
+      lookup: ssrfGuardedLookup,
       headers: {
         Accept: 'text/markdown, text/html, */*',
         'User-Agent': getWebFetchUserAgent(),

src/utils/managedEnvConstants.ts

@@ -123,7 +123,6 @@ export const SAFE_ENV_VARS = new Set([
   'ANTHROPIC_DEFAULT_SONNET_MODEL_DESCRIPTION',
   'ANTHROPIC_DEFAULT_SONNET_MODEL_NAME',
   'ANTHROPIC_DEFAULT_SONNET_MODEL_SUPPORTED_CAPABILITIES',
-  'ANTHROPIC_FOUNDRY_API_KEY',
   'ANTHROPIC_MODEL',
   'ANTHROPIC_SMALL_FAST_MODEL_AWS_REGION',
   'ANTHROPIC_SMALL_FAST_MODEL',

src/utils/plugins/marketplaceManager.ts

@@ -532,6 +532,7 @@ export async function gitPull(
 ): Promise<{ code: number; stderr: string }> {
   logForDebugging(`git pull: cwd=${cwd} ref=${ref ?? 'default'}`)
   const env = { ...process.env, ...GIT_NO_PROMPT_ENV }
+  const baseArgs = ['-c', 'core.hooksPath=/dev/null']
   const credentialArgs = options?.disableCredentialHelper
     ? ['-c', 'credential.helper=']
     : []
@@ -539,7 +540,7 @@ export async function gitPull(
   if (ref) {
     const fetchResult = await execFileNoThrowWithCwd(
       gitExe(),
-      [...credentialArgs, 'fetch', 'origin', ref],
+      [...baseArgs, ...credentialArgs, 'fetch', 'origin', ref],
       { cwd, timeout: getPluginGitTimeoutMs(), stdin: 'ignore', env },
     )
 
@@ -549,7 +550,7 @@ export async function gitPull(
 
     const checkoutResult = await execFileNoThrowWithCwd(
       gitExe(),
-      [...credentialArgs, 'checkout', ref],
+      [...baseArgs, ...credentialArgs, 'checkout', ref],
       { cwd, timeout: getPluginGitTimeoutMs(), stdin: 'ignore', env },
     )
 
@@ -559,7 +560,7 @@ export async function gitPull(
 
     const pullResult = await execFileNoThrowWithCwd(
       gitExe(),
-      [...credentialArgs, 'pull', 'origin', ref],
+      [...baseArgs, ...credentialArgs, 'pull', 'origin', ref],
       { cwd, timeout: getPluginGitTimeoutMs(), stdin: 'ignore', env },
     )
     if (pullResult.code !== 0) {
@@ -571,7 +572,7 @@ export async function gitPull(
 
   const result = await execFileNoThrowWithCwd(
     gitExe(),
-    [...credentialArgs, 'pull', 'origin', 'HEAD'],
+    [...baseArgs, ...credentialArgs, 'pull', 'origin', 'HEAD'],
     { cwd, timeout: getPluginGitTimeoutMs(), stdin: 'ignore', env },
   )
   if (result.code !== 0) {
@@ -625,6 +626,8 @@ async function gitSubmoduleUpdate(
     [
       '-c',
       'core.sshCommand=ssh -o BatchMode=yes -o StrictHostKeyChecking=yes',
+      '-c',
+      'core.hooksPath=/dev/null',
       ...credentialArgs,
       'submodule',
       'update',
@@ -810,6 +813,8 @@ export async function gitClone(
   const args = [
     '-c',
     'core.sshCommand=ssh -o BatchMode=yes -o StrictHostKeyChecking=yes',
+    '-c',
+    'core.hooksPath=/dev/null',
     'clone',
     '--depth',
     '1',

src/utils/sandbox/sandbox-adapter.ts

@@ -456,10 +456,19 @@ const checkDependencies = memoize((): SandboxDependencyCheck => {
   })
 })
 
+/**
+ * Read sandbox.enabled only from trusted settings sources.
+ * projectSettings is intentionally excluded — a malicious repo could
+ * otherwise disable the sandbox via .claude/settings.json.
+ */
 function getSandboxEnabledSetting(): boolean {
   try {
-    const settings = getSettings_DEPRECATED()
+    return !!(
-    return settings?.sandbox?.enabled ?? false
+      getSettingsForSource('userSettings')?.sandbox?.enabled ||
+      getSettingsForSource('localSettings')?.sandbox?.enabled ||
+      getSettingsForSource('flagSettings')?.sandbox?.enabled ||
+      getSettingsForSource('policySettings')?.sandbox?.enabled
+    )
   } catch (error) {
     logForDebugging(`Failed to get settings for sandbox check: ${error}`)
     return false