Architecture and design principles

The following is a merge of ENISA, OWASP and Veracode top 10. Note that there is a mixture of threats and vulnerabilities here - we should decide whether to use risks (threats with impact on assets which occur with probability) and vulnerabilities (system flaws which increase the probability of a threat occurring). I have cut those risks/vulnerabilities which cannot be addressed in any way by developers. We should decide whether to include recommendations in the style of "code of practice"- e.g. activity monitoring should only be used in circumstances xyz... (feel free to restructure)

My recommendation would be to separate out the design principles from the Risks/Vulnerabilities.

Mobile Security

• 1. Threats, Risks and Vulnerabilities
• 2. Design Principles
• 3. Architectural Patterns
• 4. Secure Mobile Development Guidelines

1. Top Risks/Vulnerabilities

• Unsafe sensitive data storage
  • Consider the whole data lifecycle in writing your application (collection over the wire, temporary storage, caching, backup, deletion etc...)
  • Automatically delete data which is not required (how to know when it's not required?).
  • Securely delete data using standard shredding techniques.
  • Store a minimum of data on the client side device.
  • Securely wipe removable media.
  • Be aware of caches and temporary storage as a possible leakage channel.
  • Implement key and password storage best practice.
  • In the design phase analyse what data needs to be protected most and what doesn't and apply controls at appropriate places.

• Unintentional disclosure of data: The smartphone user unintentionally discloses data on the smartphone.
  • Apply the principle of minimal disclosure - only collect and disclose data which is required for the application (how to know what this is?)
  • Use non-persistent identifiers wherever possible - e.g. do not use the EMEI number as an identifier unless there is a good reason to do so.
  • Apply techniques for the detection of covert channels - e.g. covert flow trees to discover information which may flow through shared resources such as file systems, resource use etc...
  • Carefully control what data which is stored in public stores such as address book, media gallery etc... including metadata.
  • Obtain user explicit user consent according to best practice (see implementation guidelines) for collection of personal data.

• Attacks on decommissioned smartphones: The smartphone is decommissioned improperly allowing an attacker access to the data on the device.
  • See first risk
  • Provide a convenient way of resetting access credentials which does not require the device (consider an automated timeout on access credentials).
  • Consider using SIM card as default storage for small but sensitive data such as keys.

• Phishing attacks: An attacker collects user credentials (such as passwords and credit card numbers) by means of fake apps or (SMS, email) messages that seem genuine.
  • Provide appropriate trust cues for linking to unknown third party applications.
  • Do not train users to follow untrusted paths.
  • Provide a reporting channel for phishing from apps (e.g. if you are a browser plugin developer).

• Spyware: Spyware covers untargeted collection of personal information as opposed to targeted surveillance.

• Network Spoofing Attacks: An attacker deploys a rogue network access point (WiFi or GSM) and users connect to it. The attacker subsequently intercepts (or tampers with) the user communication to carry out further attacks such as phishing.
  • Use the GSM encryption-on indicator to detect and signal downgrade attacks.

• Surveillance attacks: An attacker keeps a specific user under surveillance through the target user’s smartphone.
  • Don't use 3rd party code without carefully verifying
• Diallerware attacks: An attacker steals money from the user by means of malware that makes hidden use of premium SMS services or numbers.
• Financial malware attacks The smartphone is infected with malware specifically designed for stealing credit card numbers, online banking credentials or subverting online banking or ecommerce transactions.
• Network congestion Network resource overload due to smartphone usage leading to network unavailability for the end-user.
  • Note that this relies a lot on smart developers because a lot of the congestion is due to signalling overload. Could we make some recommendations on detecting idle/focus so that the app knows when it really needs to be connected to the network?
• Unauthorized network connectivity (exfiltration or command & control)
• UI Impersonation
• System modification (rootkit, APN proxy config)
  • Validate updates and input data from untrusted sources.
• Logic or Time bomb (including runtime interpreter)
  • Define clearly who should be responsible for updating the application Extensions or plugins e.g. Angry birds Add-ons and installations
• Unsafe sensitive data transmission
• Hardcoded password/keys
• Lack of data protection in transit
  • Don't allow SSL downgrade.
  • Don't trust network infrastructure
  • See Network Spoofing.
• Client-side injection
• Client-side DOS
• Malicious third-party code
  • Follow security best practice for implementation of runtime interpreters (be careful when implementing anything which turns user input into executable code).
• Client-side buffer overflow
• Failure to properly handle inbound SMS messages
  • Remove test code from software
• Failure to properly handle outbound SMS messages
• Failure to disable insecure platform features in application (caching of keystrokes, screen data)
  • Least privilege. Be aware of privileges granted by default by API's and disable them.