Security advisory: Unencrypted storage of confidential information in Keeper® Password & Data Vault v5.3 for iOS

Summary

Paul Pols of Fox-IT’s penetration testing team discovered a critical vulnerability in version 5.3 of the “Keeper® Password & Data Vault” app for iPhones, iPods touch and iPads.

An update was released today that is said to resolve the issues that we identified.

We urge all users of this application to install this update as soon as they can, because user information that the app is meant to protect, including the user’s master password, was found to be stored unencrypted.

The full advisory (that includes all technical details) can be found below.

Description: Unencrypted storage of confidential information
Affects:     Keeper® Password & Data Vault v5.3 for iOS
Vendor:      Callpod Inc. / Keeper Security Inc.
Tested on:   iOS 6.1 & iOS 6.1.2
Severity:    Critical
Discovery:   Paul Pols / Fox-IT
Reported:    18-March-2013 17:12 CET
Resolved:    04-April-2013, according to the vendor’s legal counsel
Published:   05-April-2013 16:33 CET

Background

Keeper® Password & Data Vault is a popular application that is used to store and access passwords and other confidential information. The iOS application is advertised to secure all confidential information with military-grade encryption (AES). Versions of the Keeper® software are available for multiple platforms including Android, BlackBerry, iOS, Windows Phone, Linux, Mac OS X and Windows.

 

Problem Description

Version 5.3 of the Keeper® Password & Data Vault application for iOS has been found to perform various POST-requests to keeperapp.com and/or keepersecurity.com using SSL/TLS that contain confidential information. The unencrypted content of this traffic is subsequently stored as local cache on the file system of the device. The confidential information that is posted and cached amongst others includes the unencrypted version of the master password and the content of entries that are stored within the application.

More specifically, the Keeper® Password & Data Vault application folder was found to contain SQLite3 database files in the following subdirectory /Library/Caches/D4D2433BGC/. This directory is used to store the application’s cache. The confidential information can be retrieved from the table cfurl_cache_response in the SQLite3 database or directly from the file Cache.db-wal. These unencrypted cache files are persistent across reboots.

Impact

By obtaining access to the file system of an iOS device, an attacker can retrieve confidential information from the Keeper® Password & Data Vault application directory. The information that can be retrieved includes the master password, e-mail address, the secret question and answer as well as the content of entries in the Keeper® Password & Data Vault application, such as URLs, usernames and passwords.

An attacker can obtain access to the file system of an iOS device by performing a jailbreak. Consequently, the confidentiality of information that is stored by version 5.3 (and possibly earlier versions) of the Keeper® Password & Data Vault application is at risk on iOS devices that can be jailbroken. Any iPhone, iPod touch and iPad running an iOS version up to 6.1.2 can generally be jailbroken.

Vendor response

Fox-IT has reported the vulnerability in Keeper® Password & Data Vault to Keeper Security Inc. within 24 hours of its initial discovery. Unfortunately, Keeper Security Inc. has refused to constructively engage in a responsible disclosure procedure and has requested all further communication to be addressed to the company’s legal counsel.

Keeper Security Inc’s legal counsel has since notified Fox-IT that “that the issue raised […] has been addressed and resolved in the new version of Keeper (Version 6.0) which is available on the App Store”. However, the description of the update on the App Store does not specify this version resolves any security issues. Fox-IT was also notified that the public disclosure of the issues that are described in this advisory may be met with swift legal action.

Our mission at Fox-IT is to make technical and innovative contributions for a more secure society. Given the lack of public information regarding the risks that are associated with the previous version of the application, we regard it as our responsibility to publish a detailed advisory. This will allow the affected users to take protective measures to prevent their confidential data from being compromised (further).

Solution

All confidential information that is stored on the device should be encrypted using the master password. If confidential data is stored in a remote location for backup purposes, the copy of the confidential data should also be encrypted using the master password, which should exclusively be known to the user and should not be posted or stored as such. By encrypting the confidential information that is posted to Keeper Security Inc. with the master password, the unencrypted local storage of confidential information would also be prevented.

The caching of traffic that is generated by Keeper® Password & Data Vault appears to be the result of using NSURLRequest without correctly specifying that the content of requests should not be cached. The related key ‘WebKitOfflineWebApplicationCacheEnabled’ in /Library/Preferences/D4D2433BGC.plist was found to be set to ‘true’. The unencrypted local caching of data may be prevented altogether by overriding the NSURLConnection delegate connection:willCacheResponse: and return nil. The suggested cause and solution could not be verified by Fox-IT, since Keeper Security Inc. has refused to cooperate with our investigation.

Recommendation

The local cache directly affects the confidentiality of information that is stored using version 5.3 of the Keeper® Password & Data Vault iOS application. Users of the Keeper® Password & Data Vault for iOS are therefore recommended to update the application to a version that solves the described issues or to use an alternative password manager. The risk that is posed by the unencrypted local storage of confidential information can in part be mitigated by updating the iOS operating system to a version that cannot be jailbroken and setting a device passcode, as this may temporarily prevent an attacker from obtaining access to the file system of a device.

The presence of unencrypted confidential information in the local cache of the Keeper® Password & Data Vault application indicates that an unencrypted copy of the confidential data was posted to a server that is operated by Keeper Security Inc. While the content of the confidential information is secured during transport using SSL/TLS, Keeper Security Inc receives the content of its users’ confidential information in an unencrypted form. It remains unknown which server side security measures Keeper Security Inc. has implemented to protect this information after it has been received. Consequently, the confidentiality of this information is not guaranteed from the perspective of a user. Users are therefore recommended to change any confidential information that has been entered into the affected version of the application, insofar as that is possible.

Please note that Fox-IT has not tested whether older versions of the Keeper® Password & Data Vault application and/or whether earlier iOS versions are affected by the described vulnerability. Furthermore, Fox-IT has not tested if versions of the Keeper® applications on other platforms have also posted their users’ unencrypted confidential information to Keeper Security Inc using SSL/TLS. Lastly, Fox-IT has not verified whether version 6.0 of Keeper® Password & Data Vault for iOS solves the issues that are described in this advisory.

References

Details regarding the correct usage of NSURLConnection, NSURLRequest and NSURLCache can be found here:

Using NSURLConnection: https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/URLLoadingSystem/Tasks/UsingNSURLConnection.html

Caching & NSURLConnection: http://blackpixel.com/blog/2012/05/caching-and-nsurlconnection.html

NSURLCache: http://nshipster.com/nsurlcache/

NSURLCache and disk-caching: http://petersteinberger.com/blog/2012/nsurlcache-uses-a-disk-cache-as-of-ios5/

RFC 2616: http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13