You can’t see me, I’m obfuscating (on Windows Phone)

November 17, 2010 4557 Views Sebastian Holst

Recent communications from Microsoft have resulted in a wave of interest (to put it mildly) in obfuscation. Obfuscation is not new; nor are most of the questions, concerns, and critiques that have started flying around the WP7 dev community – but some are (because there are some unique aspects to the wp7 environment).

I have included some resources and comments here – but also, please stay tuned as PreEmptive will be pushing out a collection of resources on this subject specifically targeting Windows Phone.

Quick resources available now:

ISSA Journal: Assessing and Managing Security Risks Unique to Java and .NET (pdf). Tries to answer the questions “when and why should I worry?” and “then what can I do about it?” Specifically, this article “enumerates specific risks unique to managed code (.NET and Java), offers guidance on assessing organizational materiality of these risks, and lists broadly recognized risk mitigation technologies and practices.”

WP7 FAQ (short blog form)

Question: Why do I have to obfuscate my Windows Phone application? Has Microsoft dropped the ball?

Answer: You don’t have to – but if you want to prevent easy reverse engineering of your application, then you should. Managed code has always been easy to reverse engineer (see ISSA Article listed above), and WP7 is no better or worse. In fact, it may be helpful to compare Android’s policy and recommendations on obfuscation – see my blog here for a detailed comparison.

Question: I just obfuscated my application and it’s broken! Is this a bug? Why can’t it just work like encryption?

Answer: Obfuscation is fundamentally different than encryption in that meaning matters.

Encryption is only half of the equation – the other half is decryption . Encryption algorithms do not need to preserve the meaning of content because the content will be decrypted . Meaning is wiped out in the output (that is the intent of course) and a reconstituted at decryption time (that also means that encryption cannot be lossy).

Obfuscation is the entire equation – there is no “de-obfuscation” – in fact, that is its intent. Meaning must be preserved in the final output. When your program has tricky reflection, includes mixed-mode DLLs, incorporates 3rd party libraries, etc. – all of that must be accounted for. Some of this can be divined through static analysis – but some idioms/semantics cannot.

Question: I just want to keep Reflector from showing source code. Is that so hard?

Answer: That is actually easy. Turn-off renaming and turn-on “control flow.” The ISSA article defines these transforms, but the short answer is that renaming confuses humans and control flow confuses programs. Renaming is almost always the culprit when it comes to “breaking apps.”

Question: Where can I go to learn about the latest resources to help me obfuscate my app?

Answer: Go to www.preemptive.com/application-protection - we will update this page regularly. Also, follow us on Twitter - @PreEmptive

I have also posted on some related topics

Latest Blog Posts

Announcing the DashO v10.2 Release with Resource Encryption for Android

The DashO 10.2 release introduces a major new feature: Resource Encryption for Android. It's currently in beta, but is fully supported for production use. It allows you to encrypt the resources embedded in your APK, better protecting your Android application against static attacks.

This functionality integrates directly with your existing Gradle build, encrypting the resources during the standard build process. DashO then injects code into your protected application that will decrypt those resources at runtime.

Resource Encryption is off by default, but can be easily enabled in the DashO UI. The UI makes it easy to enable, or disable, the encryption of specific resources via drag and drop. It currently supports encrypting both assets and raw resources.

Once you install DashO 10.2, using this feature is easy.

Today we're announcing the first new major-version release of Dotfuscator in thirteen years: Dotfuscator Professional 6.0 Beta. It's an exciting new release with major new capabilities, but before we get into that, let's take a look at why it's been so long since we had a major release and why we're choosing to do one now.

For development teams, adding Dotfuscator to a build pipeline can often seem like a challenge; the value it adds is mostly gained by the surrounding business, and the cost of adding it is mostly borne by the development team. We understand that constraint, which is why we focus on making Dotfuscator as easy to integrate and maintain as possible. If you're a long-time user of Dotfuscator, you've probably experienced that - release after release of painless upgrades. That's our "first do no harm" philosophy in action.

The dynamic type in C# provides flexibility that is not available in other statically-typed languages. Since its introduction in C# 4.0 (.NET 4.5), we have worked with customers who wanted to know more about how dynamic types are impacted by the obfuscation process.

Malicious actors — like any thieves — live by a simple rule: If the front door is locked, break the window.

It’s why threats like fileless malware and crypto-jacking have seen substantial gains over last few years. It’s why — despite increasing employee education and IT training — hackers are still hooking phish by developing more sophisticated and authentic-looking email spoofs. Cybercriminal communities, meanwhile, continue to grow on the dark web, allowing attackers to share info, purchase exploit kits and identify potential targets.

What does this mean for CISOs? That typical defense efforts are being outpaced as familiar attack vectors are replaced with non-traditional threats. But it’s not all bad news; here are three questions every CISO needs to ask to help close the doors, bolt the windows and leave hackers out in the cold.

Gabriel, you have been in the security industry for over 2 decades. You have seen many different tools and services. Why create a company around something as specific as obfuscation and in-app protection?

Our customers build a lot of really innovative apps that enable their users and customers to do new and cool things. These apps frequently run on untrusted client computers/devices and they control access to customer’s sensitive data or critical devices.

And after all the effort of designing, building, debugging, and deploying their applications, the last thing they want is for an attacker to steal their work or use it to look for vulnerabilities to break into their system.

Long ago, we built a Java code optimizer, but it became clear to us that our customer cared more about the obfuscation effects of the optimization than the actual performance improvement. That is when we really began to focus on app protection. First with Java, then .NET, Android, iOS, Xamarin, JavaScript, etc.

You can’t see me, I’m obfuscating (on Windows Phone)

Quick resources available now:

WP7 FAQ (short blog form)

I have also posted on some related topics

Announcing the DashO v10.2 Release with Resource Encryption for Android

Dotfuscator 6.0 Beta: Entering the Next Era of Dotfuscator

Protecting C# Applications That Use Dynamic Types

Non-Traditional Attack Vectors: Three Questions Every CISO Needs to Ask

Q&A With PreEmptive CEO Gabriel Torok

Gabriel, you have been in the security industry for over 2 decades. You have seen many different tools and services. Why create a company around something as specific as obfuscation and in-app protection?

Latest Blog Posts

Announcing the DashO v10.2 Release with Resource Encryption for Android

Dotfuscator 6.0 Beta: Entering the Next Era of Dotfuscator

Introducing JSDefender: PreEmptive Protection now includes JavaScript

Protecting C# Applications That Use Dynamic Types

Non-Traditional Attack Vectors: Three Questions Every CISO Needs to Ask

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