Sunday, June 26, 2016

Mobile Application Testing

Technology is evolving faster by the day. Today, we see mobiles are no longer mobiles, they are small computers. The smartphones run powerful applications, providing everything to users at their fingertips. Users can use their mobiles for:
  • Logging in to banks in order to transfer funds
  • Purchasing or selling shares via trading portals
  • Booking travel or movie tickets
  • Tweeting or social networking
  • Donating to charity

As money transactions move to mobiles, hackers also move their attention to it. Hence, as a precautionary measure, securing mobile applications becomes important. This article introduces you to the three key aspects of securing mobile applications.
Mobile applications may be a -
  • web application accessed via a WAP browser.
  • thick client application sending out an HTTP request or an SMS.

Security testers should broadly focus on the following categories while analyzing their test cases -
  • Local Storage of Data
  • Hard-coded Sensitive Data in the Source Code
  • Data in Transition

Let us further discuss these categories in detail from a security tester’s perspective.

Local Storage of Data
The local storage of data can also be referred to as a “Handset Memory Analysis” for mobiles.
Mobile applications store data in the local memory of a handset. This data is stored by developers in files locally and is used by the application.
  • The Android OS stores data in files at runtime, but due to its native sand-boxing mechanism, obtaining access to this data is difficult. It also stores some data in the SQLite database.
  • The Apple iOS stores sensitive information like keystrokes, snapshots and other cached information in the iPhone local memory in the form of client-side SQLite databases or .plist files.
  • The Java application in Nokia phones stores it in the form of RMS files. These RMS (Record Management System) files get stored permanently and are easily accessible. Sometimes, they are easily readable when connected to a PC via a data cable. These files have a history of containing sensitive information like bank account numbers, beneficiary details or registered biller(s) auto-pay details.

A security tester needs to conduct a Handset Memory Analysis to detect sensitive information stored in the device.
A mobile application should not store sensitive data in user handsets. If at all it is necessary to store some data, it should be stored in a secure manner using strong encryption algorithms. It can further be stored at non-reachable locations with strict permissions.

Hard-coded Sensitive Data in the Source Code
Applications are also known to comprise hard-coded data in the source code. We may come across various types of sensitive data like –
  • payment gateways hard-coding the credentials
  • applications hard-coding the server and application-specific details
  • developer names & comments explaining the code pieces

Reverse-engineer the source code to obtain readable code files. This would ultimately help discover hard-coded data. It would also help reveal the application logic.
  • Android packages the application in .apk files, which have to be reverse-engineered to .dex files and then to readable class files.
  • Other .jar files can be simply renamed to .rar and extracted by WinRAR software. This results in decompiled class files that can be read using text editors.

A security tester has to decompile the application code in order to detect sensitive data or hard-coded information.
A mobile application should not hard-code sensitive data in the client-side code.

Data in Transition
Another aspect of mobile usage is the communication channel. Data in transit may be vulnerable to sniffing or manipulation. The data in transit can be tampered or stolen to –
  • obtain access to other user accounts.
  • transfer funds from other accounts.
  • sell shares of other users in order to create a nuisance.
  • conduct social engineering.

During a security test, the tester should analyze the data in transition. The HTTP traffic in mobile networks can be intercepted via a proxy editor tool. Here, the security tester can execute targeted manipulation attacks in order to test the application’s resilience against such attacks.
Mobile applications should thus implement server-side validation to prevent data manipulation in transit. Strong SSL encryption should also be implemented to protect data in transit.

There may be various dimensions to mobile application attacks. This article attempts to focus on three key aspects of the mobile security testing domain. Most of the tests revolve around these three aspects. OWASP and other known security forums periodically release guidelines for securing mobile applications. All these guidelines should be diligently followed by developers and included in the detection armory by a security tester.

Originally written by me for Palizine Magazine in 2011 

Saturday, June 25, 2016

Mobile Security Best Practices

As mobile devices enter the work place, there is no denying their potential for improving and streamlining work processes. Companies are utilising enterprise apps that are unique to their businesses, and employees are taking full advantage of the benefits that accompany mobile business. However, with the conveniences of mobility comes the mounting threat of mobile security threats. The more that employees and contractors use mobile devices to access organizational systems, applications and data, the more important it is to protect such access.

Mobile Devices at Workplace

Traditionally, Organizations used to distribute Blackberry devices to their employees and setup the restrictions at Blackberry Enterprise Servers (BES).
Gone are those days; now Organizations are distributing high end SmartPhones to their Executives. Quite a good number of lower level Executives and Employees/Contractors bring their personal SmartPhones, which are connected to the Corporate Network.
These phones/tablets have different Operating Systems, like Android, iOS, Windows 7 or 8 etc. and have sufficient enough computation and capabilities to hack or cause nuisance.

Types of Applications

There can be multiple classifications of mobile applications-
  1. Native v/s WAP v/s Hybrid apps.
  2. Apps developed for inhouse employees v/s Apps developed for consumers.
  3. Free v/s Commercial apps.

Threats to Enterprises
Data is the critical asset of Enterprises. Below threats pose risks related to data compromise via mobile devices-
  1. Lost devices.
  2. Temporarily unattended devices.
  3. Malwares/Rouge Applications in devices.
  4. Devices under control of remote attackers via internet, Bluetooth, NFC etc.
  5. Jailbroken or Rooted devices.
  6. Leaked Domain Credentials for WPA2-PEAP WiFi.
  7. Lacking accountability or traceability for mobiles in enterprises.
  8. Missing/Mis-configured encryption for data at rest and transit.

Mobile Application Development Security
Most vulnerability in the mobile applications, result from bad programming and can be avoided by following few quick tips, by all developers irrespective of their development platform:
  1. Do not hardcode secrets like passwords, encryption key in the client side source code.
  2. Do not store passwords or other sensitive data in the phone.
  3. Use SSL for sensitive data transfer.
  4. Use appropriately strong encryption for data at rest.
  5. Authenticate users, sanitize inputs and manage sessions appropriately.
  6. Do not print/store sensitive data in console, logs or cache.
  7. Check security of 3rd party libraries in use.
  8. Secure the backend components (web servers, web services and hosting).

Mobile Device Security
Here are the few tips for end users to keep the mobiles/tablets secured:
  1. Set a password lock (numeric or graphical).
  2. Set Device auto-lock.
  3. Install a good anti-virus.
  4. Keep the device firmware updated.
  5. Pair only to trusted Bluetooth devices or NFC peers.
  6. Always download applications from trusted App Stores.
  7. Visit HTTPS secured and reputed websites only.
  8. Do not jailbreak or root your device.
  9. Connect to secure/trusted WiFi networks.

Additionally, few tips for enterprises to safeguard their employee mobiles and data:
  1. Use Disk Encryption for mobile devices.
  2. Employ Disk Encryption for SD cards too, if users store corporate date there.
  3. Secure WiFi with strong WPA2 PEAP (Domain based) or Certificate based authentication.
  4. Employ remote data wipe.
  5. Use mobile device data backup solutions.
  6. Maintain an inventory of user devices allowed to connect to corporate network.
  7. Maintain an inventory of allowed mobile applications for work.
  8. Have a fair usage policy and systems to control usage.
  9. Enterprises having their private AppStores, must take care of distributing secure applications only.

BYOD as an opportunity for Enterprises
BYOD concept allows employees to use their devices at work and BYOD Solutions allows enterprises to control the Employee device security by building restrictions, controls and policies around it. Different BYOD Solutions offer variety of security features. Some useful ones are-
  1. AppStore owned by Employers, for providing work related apps to employees.
  2. Unified security policies enforcement across organization.
  3. Access control and auditing.
  4. Selective data wipe for corporate data.
  5. Certificate Authority and Certificate based security.
  6. Secure file sharing.
  7. Device Registration mechanism.

A lot a have been spoken and written over time on mobile security. OWASP runs a mobile security project, NIST has released Mobile Device Security Guidelines for Enterprises, hacking and security companies have release free and paid tools for mobile app security assessments, apart from the commercial MDM solutions. Adaptation of all of these approaches in tandem is necessary to implement security by “defence in depth” approach.
Three final tips to Enterprise Mobile Security. Firstly, harden the mobile devices; encourage users for the same, go for forceful implementation if required. Secondly, ensure that mobile applications are secure via SAST and DAST approaches. Finally, implement a suitable BYOD solution and setup security policies for end users.