Error while decompiling the obfuscated Dll

2 posts, 0 answers
  1. satya
    satya avatar
    1 posts
    Member since:
    Jul 2014

    Posted 05 Jun 2015 Link to this post

    Hi ,

     I have obfuscated an XAP using Dotfuscator.I was trying to validate whether the XAP got obfuscated or not.

    1. When i was de-compiling the Obfuscated Dll using Telerik JustDecompile,it says followling error.

    Specified argument was out of the range of valid values.
    at Mono.Collections.Generic.Collection`1..ctor(Int32 capacity) in X:\XXXX\XXXX\XXXX\XXXX XXXX XXXX\XXX\XXX\Mono.Cecil\Mono.Collections.Generic\Collection.cs:l
    at Mono.Cecil.MetadataReader.ReadMethods(TypeDefinition type) in X:\XXX\XXX\XXXX\XXX XXX XXX\XXX\XXX\Mono.Cecil\Mono.Cecil\AssemblyReader.cs:line XXX.

     2.  When i was trying to load the Xap(obfuscated) from decompile(steps: open->XAp URL),It got loaded successfully,when i tried expanding the child items(clicked on expander in the left pane),It rotates forever and not even giving any error.

    Can i assume that,XAP is obfuscated successfully if justdecompile is unable to get the source code back.




  2. Alexander
    Alexander avatar
    336 posts

    Posted 10 Jun 2015 Link to this post

    Hi Satya,

    The XAP files are plain ZIP files, hence they cannot be obfuscated. However the DLL files in the XAP file could be.

    Opening an obfuscated assembly in JustDecompile is not a supported scenario. If JustDecompile successfully decompiles the non-obfuscated version of your XAP file but fails on the obfuscated one then you can safely assume obfuscation worked for you.

    However, keep in mind that some of the deobfuscators out there could possibly deobfuscate it successfully. In this case there is a chance JustDecompile to open it and show the source code. E.g. JustDecompile offers the de4dot plugin that does just that.

    If you need further assistance, please, do not hesitate to contact us.

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