HexRaysCodeXplorer: make object-oriented RE easier

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HexRaysCodeXplorer - Hex-Rays Decompiler plugin for easier code navigation. Here are the main features of the plugin:
- Automatic type REconstruction for C++ objects.
- C-tree graph visualization – a special tree-like structure representing a decompiled routine in c_itemt terms. Useful feature for understanding how the decompiler works.
- Navigation through virtual function calls in HexRays Pseudocode window.
- Object Explorer – useful interface for navigation through virtual tables (VTBL) structures.

In this presentation authors of HexRaysCodeXplorer will be discussing main functionality of the plugin and its application for reverse engineering. The authors will be presenting the algorithm for C++ type REconstruction. Also a special version of HexRaysCodeXplorer (ZeroNigths edition) will be released with new features developed specially for ZeroNights conference. New features will be committed GitHub from the stage

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HexRaysCodeXplorer: make object-oriented RE easier

  1. 1. HexRaysCodeXplorer: make object-oriented RE easier Aleksandr MatrosovEugene Rodionov @matrosov @vxradius
  2. 2. C++ Code Reconstruction Problems  Object identification  Type reconstruction  Class layout reconstruction     Identify constructors/destructors Identify class members Local/global type reconstruction Associate object with exact method calls  RTTI reconstruction  Vftable reconstruction  Associate vftable object with exact object  Class hierarchy reconstruction
  3. 3. C++ Code Reconstruction: the truth is out there
  4. 4. An overview of the Flamer Framework Vector<Command Executor> Vector<Consumer> DB_Query ClanCmd FileCollect Driller GetConfig Munch FileFinder Mobile Consumer Cmd Consumer Vector<Task> IDLER CmdExec Sniffer Lua Consumer Vector<DelayedTasks> Media Consumer Euphoria Share Supplier LSS Sender Frog Beetlejuice
  5. 5. An overview of the Flamer Framework Vector<Command Executor> Vector<Consumer> DB_Query ClanCmd FileCollect Driller GetConfig Munch FileFinder Mobile Consumer Cmd Consumer Vector<Task> IDLER CmdExec Sniffer Lua Consumer Vector<DelayedTasks> Media Consumer Euphoria Share Supplier LSS Sender Frog Beetlejuice
  6. 6. An overview of the Flamer Framework Vector<Command Executor> Vector<Consumer> DB_Query ClanCmd FileCollect Driller GetConfig Munch FileFinder Mobile Consumer Cmd Consumer Vector<Task> IDLER CmdExec Sniffer Lua Consumer Vector<DelayedTasks> Media Consumer Euphoria Share Supplier LSS Sender Frog Beetlejuice
  7. 7. HexRaysCodeXplorer
  8. 8. HexRaysCodeXplorer Features  Hex-Rays decompiler plugin  The plugin was designed to facilitate static analysis of:  object oriented code  position independent code  The plugin allows to:  navigate through decompiled virtual methods  partially reconstruct object type
  9. 9. Hex-Rays Decompiler Plugin SDK  At the heart of the decompiler lies ctree structure:  syntax tree structure  consists of citem_t objects  there are 9 maturity levels of the ctree structure
  10. 10. Hex-Rays Decompiler Plugin SDK  At the heart of the decompiler lies ctree structure:  syntax tree structure  consists of citem_t objects  there are 9 maturity levels of the ctree structure
  11. 11. Hex-Rays Decompiler Plugin SDK  Type citem_t is a base class for:  cexpr_t – expression type  cinsn_t – statement type citem_t cexpr_t cinsn_t  Expressions have attached type information  Statements include:  block, if, for, while, do, switch, return, goto, asm  Hex-Rays provides iterators for traversing the citem_t objects within ctree structure:  ctree_visitor_t  ctree_parentee_t
  12. 12. Hex-Rays Decompiler Plugin SDK  Type citem_t is a base class for:  cexpr_t – expression type  cinsn_t – statement type citem_t cexpr_t cinsn_t  Expressions have attached type information  Statements include:  block, if, for, while, do, switch, return, goto, asm  Hex-Rays provides iterators for traversing the citem_t objects within ctree structure:  ctree_visitor_t  ctree_parentee_t
  13. 13. HexRaysCodeXplorer: Gapz Position Independent Code
  14. 14. HexRaysCodeXplorer: Virtual Methods  The IDA’s “Local Types” is used to represent object type
  15. 15. HexRaysCodeXplorer: Virtual Methods  Hex-Rays decompiler plugin is used to navigate through the virtual methods
  16. 16. HexRaysCodeXplorer: Virtual Methods  Hex-Rays decompiler plugin is used to navigate through the virtual methods
  17. 17. HexRaysCodeXplorer: Object Type REconstruction  Hex-Rays’s ctree structure may be used to partially reconstruct object type based on its initialization routine (constructor)  Input:  pointer to the object instance  object initialization routine entry point  Output:  C structure-like object representation
  18. 18. HexRaysCodeXplorer: Object Type REconstruction  Hex-Rays’s ctree structure may be used to partially reconstruct object type based on its initialization routine (constructor)  Input:  pointer to the object instance  object initialization routine entry point  Output:  C structure-like object representation
  19. 19. HexRaysCodeXplorer: Object Type REconstruction  citem_t objects to monitor:  memptr  call (LOBYTE, etc.)  idx  memref
  20. 20. HexRaysCodeXplorer: Object Type REconstruction // reference of DWORD at offset 12 in buffer a1 *(DWORD *)(a1 + 12) = 0xEFCDAB89;
  21. 21. HexRaysCodeXplorer: Object Type REconstruction // reference of DWORD at offset 12 in buffer a1 *(DWORD *)(a1 + 12) = 0xEFCDAB89;
  22. 22. HexRaysCodeXplorer 1.1 [ZeroNights Edition]  Type Reconstruction:  reconstruct type into IDA local types  bugfixes =)  ObjectExplorer:  Auto structures for VTBL  Click on VTBL and jump to code  ObjectExplorer hints for VTBL
  23. 23. NO TIME for DEMO
  24. 24. Thank you for your attention! Eugene Rodionov Aleksandr Matrosov @vxradius @matrosov

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