Re: [FD] Xamarin for Android <5.1 DLL Hijack Vulnerability

[Tim <strazz@xxxxxxxxx>]

Thanks for posting this to FD, these didn't even include it in their
release notes;

http://developer.xamarin.com/releases/android/xamarin.android_5/xamarin.android_5.1/

Was there a bug reported in bugzilla to link back too?

-Tim Strazzere

On Tue, May 19, 2015 at 6:49 AM, ValdikSS <iam@xxxxxxxxxxxxxxx> wrote:

>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
>
> Xamarin for Android prior to version 5.1 allows to replace internal DLL
> files inside the APK with files on SD card which are not in a secure
> storage.
> Malicious application without any special permissions could drop
> backdoored DLL files into
>
> /storage/sdcard0/Android/data/app_id/files/.__override__/
>
> and the victim application would use files from SD.
> Not just the main application library could be hijacked, but also
> Xamarin's System.dll and Mono.Android.dll, which are shipped in all Xamarin
> for Android
> applications.
>
> Developers should rebuild their applications using Xamarin for Android 5.1
> or newer in the release mode.
>
> This vulnerability was found by accident, which allowed me to eat for free
> for a month.
>
> Timeline:
>     03.04.2015 Vulnerability is found
>     07.04.2015 Message sent to Xamarin
>     08.04.2015 Xamarin acknowledged the vulnerability
>     29.04.2015 Fixed stable version released
>
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