diff --git a/apps/files_external/lib/Controller/AjaxController.php b/apps/files_external/lib/Controller/AjaxController.php
index 8dcfb2a47e..068abbb809 100644
--- a/apps/files_external/lib/Controller/AjaxController.php
+++ b/apps/files_external/lib/Controller/AjaxController.php
@@ -26,25 +26,48 @@ namespace OCA\Files_External\Controller;
 
 use OCA\Files_External\Lib\Auth\Password\GlobalAuth;
 use OCP\AppFramework\Controller;
+use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\Response;
+use OCP\IGroupManager;
 use OCP\IRequest;
 use OCP\AppFramework\Http\JSONResponse;
 use OCA\Files_External\Lib\Auth\PublicKey\RSA;
+use OCP\IUserSession;
 
 class AjaxController extends Controller {
 	/** @var RSA */
 	private $rsaMechanism;
 	/** @var GlobalAuth  */
 	private $globalAuth;
+	/** @var IUserSession */
+	private $userSession;
+	/** @var IGroupManager */
+	private $groupManager;
 
+	/**
+	 * @param string $appName
+	 * @param IRequest $request
+	 * @param RSA $rsaMechanism
+	 * @param GlobalAuth $globalAuth
+	 * @param IUserSession $userSession
+	 * @param IGroupManager $groupManager
+	 */
 	public function __construct($appName,
 								IRequest $request,
 								RSA $rsaMechanism,
-								GlobalAuth $globalAuth) {
+								GlobalAuth $globalAuth,
+								IUserSession $userSession,
+								IGroupManager $groupManager) {
 		parent::__construct($appName, $request);
 		$this->rsaMechanism = $rsaMechanism;
 		$this->globalAuth = $globalAuth;
+		$this->userSession = $userSession;
+		$this->groupManager = $groupManager;
 	}
 
+	/**
+	 * @return array
+	 */
 	private function generateSshKeys() {
 		$key = $this->rsaMechanism->createKey();
 		// Replace the placeholder label with a more meaningful one
@@ -70,13 +93,26 @@ class AjaxController extends Controller {
 	}
 
 	/**
+	 * @NoAdminRequired
+	 *
 	 * @param string $uid
 	 * @param string $user
 	 * @param string $password
 	 * @return bool
 	 */
 	public function saveGlobalCredentials($uid, $user, $password) {
-		$this->globalAuth->saveAuth($uid, $user, $password);
-		return true;
+		$currentUser = $this->userSession->getUser();
+
+		// Non-admins can only edit their own credentials
+		$allowedToEdit = (
+			$this->groupManager->isAdmin($currentUser->getUID()) || $currentUser->getUID() === $uid
+		) ? true : false;
+
+		if ($allowedToEdit) {
+			$this->globalAuth->saveAuth($uid, $user, $password);
+			return true;
+		} else {
+			return false;
+		}
 	}
 }
diff --git a/apps/files_external/tests/Controller/AjaxControllerTest.php b/apps/files_external/tests/Controller/AjaxControllerTest.php
new file mode 100644
index 0000000000..c51172f899
--- /dev/null
+++ b/apps/files_external/tests/Controller/AjaxControllerTest.php
@@ -0,0 +1,177 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Lukas Reschke <lukas@statuscode.ch>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+namespace OCA\Files_External\Tests\Controller;
+
+use OCA\Files_External\Controller\AjaxController;
+use OCA\Files_External\Lib\Auth\Password\GlobalAuth;
+use OCA\Files_External\Lib\Auth\PublicKey\RSA;
+use OCP\AppFramework\Http\JSONResponse;
+use OCP\IGroupManager;
+use OCP\IRequest;
+use OCP\IUserSession;
+use Test\TestCase;
+
+class AjaxControllerTest extends TestCase {
+	/** @var IRequest */
+	private $request;
+	/** @var RSA */
+	private $rsa;
+	/** @var GlobalAuth */
+	private $globalAuth;
+	/** @var IUserSession */
+	private $userSession;
+	/** @var IGroupManager */
+	private $groupManager;
+	/** @var AjaxController */
+	private $ajaxController;
+
+	public function setUp() {
+		$this->request = $this->getMock('\\OCP\\IRequest');
+		$this->rsa = $this->getMockBuilder('\\OCA\\Files_External\\Lib\\Auth\\PublicKey\\RSA')
+			->disableOriginalConstructor()
+			->getMock();
+		$this->globalAuth = $this->getMockBuilder('\\OCA\\Files_External\\Lib\\Auth\\Password\GlobalAuth')
+			->disableOriginalConstructor()
+			->getMock();
+		$this->userSession = $this->getMock('\\OCP\\IUserSession');
+		$this->groupManager = $this->getMock('\\OCP\\IGroupManager');
+
+		$this->ajaxController = new AjaxController(
+			'files_external',
+			$this->request,
+			$this->rsa,
+			$this->globalAuth,
+			$this->userSession,
+			$this->groupManager
+		);
+
+		parent::setUp();
+	}
+
+	public function testGetSshKeys() {
+		$this->rsa
+			->expects($this->once())
+			->method('createKey')
+			->willReturn([
+				'privatekey' => 'MyPrivateKey',
+				'publickey' => 'MyPublicKey',
+			]);
+
+		$expected =  new JSONResponse(
+			[
+				'data' => [
+					'private_key' => 'MyPrivateKey',
+					'public_key' => 'MyPublicKey',
+				],
+				'status' => 'success',
+			]
+		);
+		$this->assertEquals($expected, $this->ajaxController->getSshKeys());
+	}
+
+	public function testSaveGlobalCredentialsAsAdminForAnotherUser() {
+		$user = $this->getMock('\\OCP\\IUser');
+		$user
+			->expects($this->once())
+			->method('getUID')
+			->willReturn('MyAdminUid');
+		$this->userSession
+			->expects($this->once())
+			->method('getUser')
+			->willReturn($user);
+		$this->groupManager
+			->expects($this->once())
+			->method('isAdmin')
+			->with('MyAdminUid')
+			->willReturn(true);
+		$this->globalAuth
+			->expects($this->once())
+			->method('saveAuth')
+			->with('UidOfTestUser', 'test', 'password');
+
+		$this->assertSame(true, $this->ajaxController->saveGlobalCredentials('UidOfTestUser', 'test', 'password'));
+	}
+
+	public function testSaveGlobalCredentialsAsAdminForSelf() {
+		$user = $this->getMock('\\OCP\\IUser');
+		$user
+			->expects($this->once())
+			->method('getUID')
+			->willReturn('MyAdminUid');
+		$this->userSession
+			->expects($this->once())
+			->method('getUser')
+			->willReturn($user);
+		$this->groupManager
+			->expects($this->once())
+			->method('isAdmin')
+			->with('MyAdminUid')
+			->willReturn(true);
+		$this->globalAuth
+			->expects($this->once())
+			->method('saveAuth')
+			->with('MyAdminUid', 'test', 'password');
+
+		$this->assertSame(true, $this->ajaxController->saveGlobalCredentials('MyAdminUid', 'test', 'password'));
+	}
+
+	public function testSaveGlobalCredentialsAsNormalUserForSelf() {
+		$user = $this->getMock('\\OCP\\IUser');
+		$user
+			->expects($this->exactly(2))
+			->method('getUID')
+			->willReturn('MyUserUid');
+		$this->userSession
+			->expects($this->once())
+			->method('getUser')
+			->willReturn($user);
+		$this->groupManager
+			->expects($this->once())
+			->method('isAdmin')
+			->with('MyUserUid')
+			->willReturn(false);
+		$this->globalAuth
+			->expects($this->once())
+			->method('saveAuth')
+			->with('MyUserUid', 'test', 'password');
+
+		$this->assertSame(true, $this->ajaxController->saveGlobalCredentials('MyUserUid', 'test', 'password'));
+	}
+
+	public function testSaveGlobalCredentialsAsNormalUserForAnotherUser() {
+		$user = $this->getMock('\\OCP\\IUser');
+		$user
+			->expects($this->exactly(2))
+			->method('getUID')
+			->willReturn('MyUserUid');
+		$this->userSession
+			->expects($this->once())
+			->method('getUser')
+			->willReturn($user);
+		$this->groupManager
+			->expects($this->once())
+			->method('isAdmin')
+			->with('MyUserUid')
+			->willReturn(false);
+
+		$this->assertSame(false, $this->ajaxController->saveGlobalCredentials('AnotherUserUid', 'test', 'password'));
+	}
+}