This encrypts the binary so that decryption keys are needed in order to make the binary readable. Similarly to the previous section, encryption shouldn't be a concern for most iOS developers, since the App Store takes care of it during the distribution process.įrom iPhoneDev's Wiki: App Store binaries are signed by both their developer and Apple. Since this process is required by Apple for most operations, if this section is flagged as "False" by MobSF, it's likely that the file you're analysing was generated via some non-traditional method, which seems worth investigating. So, code signing is simply the process of signing an application with an appropriate certificate that ensures the author's identity and the app content's integrity. The real-world identity of each developer, whether an individual or a business, is verified by Apple before their certificate is issued.Īt runtime, code signature checks of all executable memory pages are made as they are loaded to ensure that an app has not been modified since it was installed or last updated. v print verbosely (symbolically) when possible Code Signatureįrom the Apple docs on Code Signing we can read: Before your app can integrate app services, be installed on a device, or be submitted to the App Store, it must be signed with a certificate issued by Apple.Īlso, from the iOS Security Guide: In order to develop and install apps on iOS devices, developers must register with Apple and join the iOS Developer Program. Note the usage of otool's -I and -v flags: ~ otool When it comes to ARC we can use this tool to check for the presence of ARC-related symbols, such as _objc_release, _objc_autorelease, _objc_storeStrong, _objc_retain, etc.: Since there are limitations that come with using ARC, the adequacy of these exceptions should be evaluated on a case by case basis.Īs mentioned above, otool can help us understand our binary files a little better. You can also check the "Compile Sources" section under the "Build Phases" tab for the presence of the -fno-objc-arc flag, which is used to exclude specific files from using ARC, as shown below: If this property is set to No, you should "Convert" the project, as shown below: So, if your application is written (at least partially) in Objective-C, you should first make sure that the project is configured to use ARC by checking the "Objective-C Automatic Reference Counting" setting under the "Build Settings" tab: The alternative is to leave memory management to the developer, who is always less reliable and can easily make mistakes that can lead to memory corruption vulnerabilities. If you've never heard of "Automatic Reference Counting" you should basically know that it "automatically frees up the memory used by class instances when those instances are no longer needed". However, ARC is actually a feature of the Clang compiler, and unlike with Swift, you can (but shouldn't) use Objective-C without using Automatic Reference Counting. If you're used to working with Swift, then you most likely know ARC or "Automatic Reference Counting" simply as one of the core features of the language. You should become familiar with this tool since it will help us validate and fix most of the issues reported below.Īlternatively, I also recommend htool, which serves the similar purpose of analysing Mach-O binaries. ipa it's time to unzip it and look inside: ~ unzip MyApp.ipaĪs you can see above, the app binary is compiled for ARM and uses the Mach-O file format.Ī more thorough analysis of this binary can be done using otool. ~ ipatool download -bundle-identifier -email -password ipa you can extract it from the App Store using ipatool: ~ brew tap majd/repo Note that if you don't have access to the. When we talk about binary analysis, we're actually just talking about analysing this executable file, so the first thing we need to do is find it. ipa files are actually just zipped files that include the application executable and a bunch of other stuff. Hopefully this article will help you understand why each vulnerability was reported and how to fix it. ipa, the "IPA Binary Analysis" section can report multiple issues that can be hard to interpret. MobSF is an open source static and dynamic analysis tool for Android and iOS, which can be used to quickly detect major issues on your mobile application.
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