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Thread: help with a multi(?) packed .dll

  1. #1
    Exocist
    Guest

    help with a multi(?) packed .dll

    hi chaps,

    first off, I confess to being a lurker around these parts since Splaj helped me a long time ago on BeatCreator 1.4

    anyway, since then I been unpacking the odd thing but this one has me puzzled. The packed .dll is called SynSonos.dll and it part of the Cubase SX protection created by SynchroSoft. Natively, this .dll doesn't come packed.

    The packing of the .dll has been introduced by the group that cracked it, in this case ZONE Team. As part of their crack they have used SetWindowTextA and LoadBitmapA to replace the splash screen and it's caption. I like to NOP these out and ADD ESP,08 to compenstate. This works fine to keep the original splash intact.

    I have already done this with this .dll, I dumped the .dll with IceDump at the OEiP = 0x0000C604, fixed the API calls above and it works fine. BUT... I want to unpack this .dll a different way without dumping. This is what I'm really interested in as the .dll appears to be packed with UPX and ASPack 2.xx

    The header sigiture in the .dll would indicate it is UPX, esp at offset 0x000003E0 where there would normally be a "UPX!", the section names have been removed.

    However, after LoadLibraryA is called the first jump into the .dll is address offset 0x00028200 and this appears to me to be ASPack, it get's to the end of this routine, pushes the address to the UPX de-packer;

    PUSH 02FE2F00 <--- depending where it loaded in memory; base addy + 52F000
    RET

    the UPX process runs and pushes a return address back to another ASPack de-packer;

    PUSH 02FDE000 <--- or base address + 4E000
    RET

    this then does it's thing and FINALLY it jumps into the REAL OEiP of the unpacked library;

    PUSH 02F9C604
    RET

    long-winded I know. I need some advice on how to unpack this, it seems to me that only certain sections of the .dll are being unpacked. I basically want to end up with an unpacked .dll exactly as it was before any packer was applied.

    I've tried the obvious like using ASPackDie (which complains about not knowing the exact compressor version) but 'appears' to successfully unpack part of the .dll, it updates the EIP with the offset pointing to the UPX routine. Then I thought... OK lets replace the UPX0 , UPX1 etc... in the section names and try to uncompress the next bit with UPX -d... no joy.

    I would love someone to take a look at it and point out what I'm missing. I would have thouht that if a file was packed like this;

    1) ASPack <file>
    2) UPX -f <file>
    3) ASPack <file>

    then the process could be reversed, unless... only certain sections have been packed.

    if anyway is interested, for curiousity sake, then please email me;

    exosys(at)yahoo.com

    and I'll send you the .dll in question. thanks guys...

    -Ex

    PS: I have also dumped this .dll with lordpe and rebuilt the IAT using revirgin (IAT=0x0002015C) also.. that work too.
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  2. #2
    Lbolt99
    Guest
    They might have packed with a modified version of UPX. I have seen it floating around. It confuses UPX so that the -d option doesn't work. I think they just change some of the starting code to screw it up. Not sure if that's the problem you're running into though.

    Update:
    Just ran into something called UPXFIX on exetools, you might want to take a look at that, might fix your upx -d prob.. also ASpackDie 1.4 is out
    Last edited by Lbolt99; August 3rd, 2002 at 06:55.
    I promise that I have read the FAQ and tried to use the Search to answer my question.

  3. #3
    Exocist
    Guest
    thanks for the reply man,

    I've been working on this for a few days now and it's pretty much done.

    1) I did the first ASPack with ASPackDie, this got rid of two sections in the .dll, I had to patch two bytes in the UPX unpack routines after doing this, these bytes were the addy being loaded into LEA ESI at the start of the UPX routines.

    2) I then let the UPX routines do their thing and set a breakpoint on the start of the second ASPack routine

    3) I nursed the ASPack routine thru, it unpacked about 8 sections of the .dll, at each time I took the starting address in EDI, and the length from EAX and dumped each section as it was unpacked, this also allowed me to get the original IAT before it was destroyed.

    4) I put the .dll back together section by section, modifed the pointers to the IAT , modied pointers to the .RSRC section and the .EDATA sections. (the pointer modifying was a bitch but I learnt heaps)

    Now I have a unpacked .dll that is clean of unpacker code and it works... a good learning curve for me.

    I have a question tho, does ASPack keep the original file header to get offsets from? I found that during the unpacking stage it was delving into 0xBFF70000 which contained this header...

    Code:
    00000000 4D5A 9000 0300 0000 0400 0000 FFFF 0000 B800 0000 0000 0000 4000 0000 0000 0000 MZ......................@.......
    00000020 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 8000 0000 ................................
    00000040 0E1F BA0E 00B4 09CD 21B8 014C CD21 5468 6973 2070 726F 6772 616D 2063 616E 6E6F ........!..L.!This program canno
    00000060 7420 6265 2072 756E 2069 6E20 444F 5320 6D6F 6465 2E0D 0D0A 2400 0000 0000 0000 t be run in DOS mode....$.......
    00000080 5045 0000 4C01 0500 B3C2 1F37 0000 0000 0000 0000 E000 0F21 0B01 030A 0060 0500 PE..L......7...........!.....`..
    000000A0 008A 0100 0000 0000 6F4B 0100 0010 0000 0090 0500 0000 F7BF 0010 0000 0010 0000 ........oK......................
    000000C0 0400 0000 0100 0900 0400 0000 0000 0000 0030 0700 0004 0000 692E 0800 0200 0000 .................0......i.......
    000000E0 0000 1000 0010 0000 0080 0000 0010 0000 0000 0000 1000 0000 5009 0500 B54F 0000 ........................P....O..
    00000100 0000 0000 0000 0000 00D0 0500 4057 0100 0000 0000 0000 0000 0000 0000 0000 0000 ............@W..................
    00000120 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 ................................
    00000140 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 ................................
    00000160 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 5F46 5245 5141 534D ........................_FREQASM
    00000180 0470 0000 0010 0000 0080 0000 0010 0000 0000 0000 0000 0000 0000 0000 2000 0060 .p.......................... ..`
    000001A0 2E74 6578 7400 0000 05C9 0400 0090 0000 00D0 0400 0090 0000 0000 0000 0000 0000 .text...........................
    000001C0 0000 0000 2000 0060 5F49 4E49 5400 0000 4123 0000 0060 0500 0030 0000 0060 0500 .... ..`_INIT...A#...`...0...`..
    000001E0 0000 0000 0000 0000 0000 0000 2000 00D0 2E64 6174 6100 0000 9A30 0000 0090 0500 ............ ....data....0......
    00000200 0040 0000 0090 0500 0000 0000 0000 0000 0000 0000 4000 00D0 2E72 7372 6300 0000 .@..................@....rsrc...
    00000220 4057 0100 00D0 0500 0060 0100 00D0 0500 0000 0000 0000 0000 0000 0000 4000 0040 @W.......`.....
    thanks for your help again LBolt

    -Ex
    I promise that I have read the FAQ and tried to use the Search to answer my question.

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