[CVE-2014-0647] Insecure Data Storage of User Data Elements in Starbucks v2.6.1 iOS mobile application

2014-01-1900:00:00

vulners.com

Title: [CVE-2014-0647] Insecure Data Storage of User Data Elements in Starbucks v2.6.1 iOS mobile application
Published: January 13, 2014
Reported to Vendor: December 2013 (no direct response)
CVE Reference: CVE-2014-0647
Credit: This issue was discovered by Daniel E. Wood
http://www.linkedin.com/in/danielewood

Product: Starbucks iOS mobile application
Version: 2.6.1 (May 02, 2013)
Vendor: Starbucks Coffee Company
URL: https://itunes.apple.com/us/app/starbucks/id331177714

Issue: Username, email address, and password elements are being stored in clear-text in the session.clslog crashlytics log file.
Location: /Library/Caches/com.crashlytics.data/com.starbucks.mystarbucks/session.clslog

Within session.clslog there are multiple instances of the storage of clear-text credentials that can be recovered and leveraged for unauthorized usage of a users account on the malicious users’ own device or online at https://www.starbucks.com/account/signin. It contains the HTML of the mobile application page that performs the account login or account reset. session.clslog also contains the OAuth token (signed with HMAC-SHA1) and OAuth signature for the users account/device to the Starbucks service.

From session.clslog:
<div class="block_login">
<form action="/OAuth/sign-in" class="siren" id="accountForm" method="post">
<fieldset class="login_position">
<legend><span class="group-header">I have a Starbucks account.</span></legend>

	[...snip...]
	
	&lt;li&gt;
		&lt;label for=&quot;Account_UserName&quot; class=&quot;&quot;&gt;Username &lt;span class=&#39;req&#39;&gt;*&lt;/span&gt;&lt;/label&gt;
		&lt;span class=&quot;x&quot;&gt;
			&lt;input class=&quot;field text medium&quot; id=&quot;Account_UserName&quot; maxlength=&quot;200&quot; name=&quot;Account.UserName&quot; tabindex=&quot;0&quot; type=&quot;text&quot; value=&quot;CLEARTEXT&quot; /&gt;
			&lt;/span&gt;
	&lt;/li&gt;
	&lt;li&gt;
		&lt;label for=&quot;Account_PassWord&quot; class=&quot;&quot;&gt;Password &lt;span class=&#39;req&#39;&gt;*&lt;/span&gt;&lt;/label&gt;
		&lt;span class=&quot;x&quot;&gt;
			&lt;input class=&quot;field text medium&quot; id=&quot;Account_PassWord&quot; maxlength=&quot;200&quot; name=&quot;Account.PassWord&quot; tabindex=&quot;0&quot; type=&quot;password&quot; value=&quot;CLEARTEXT&quot; /&gt;
		&lt;/span&gt;
	&lt;/li&gt;

43440 $ -[AccountManager forgotPasswordEmail:withUserName:] line 1609 $ BODY STRING:[ {"emailAddress":"CLEARTEXT","userName":"CLEARTEXT"} ]

Note: All references of 'CLEARTEXT' above are the cleartext values of each referenced string.

Mitigation:
To prevent sensitive user data (credentials) from being recovered by a malicious user, output sanitization should be conducted to prevent these data elements from being stored in the crashlytics log files in clear-text, if at all.

iOS Specific Best Practices (from OWASP Mobile Top 10 - M1 Insecure Data Storage):

Never store credentials on the phone file system. Force the user to authenticate using a standard web or API login scheme (over HTTPS) to the application upon each opening and ensure session timeouts are set at the bare minimum to meet the user experience requirements.
Where storage or caching of information is necessary consider using a standard iOS encryption library such as CommonCrypto
If the data is small, using the provided apple keychain API is recommended but, once a phone is jailbroken or exploited the keychain can be easily read. This is in addition to the threat of a bruteforce on the devices PIN, which as stated above is trivial in some cases.
For databases consider using SQLcipher for Sqlite data encryption
For items stored in the keychain leverage the most secure API designation, kSecAttrAccessibleWhenUnlocked (now the default in iOS 5) and for enterprise managed mobile devices ensure a strong PIN is forced, alphanumeric, larger than 4 characters.
For larger or more general types of consumer-grade data, Apple’s File Protection mechanism can safely be used (see NSData Class Reference for protection options).
Avoid using NSUserDefaults to store senstitve pieces of information as it stores data in plist files.
Be aware that all data/entities using NSManagedObects will be stored in an unencrypted database file.

References:
http://try.crashlytics.com/security/
https://developer.apple.com/library/mac/documentation/Security/Conceptual/SecureCodingGuide/SecurityDevelopmentChecklists/SecurityDevelopmentChecklists.html#//apple_ref/doc/uid/TP40002415-CH1-SW1
https://www.owasp.org/index.php/IOS_Developer_Cheat_Sheet#Insecure_Data_Storage_.28M1.29