Advantage And Disadvantage

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Advantage And Disadvantage

• Advantage
• Reduced Risk
• Reduced Cost
• Disadvantage
• There are practical limits to the extent that a
  system can be improved by re-engineering
• ?? ?????

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Software Re-Engineering

• Process
• Source Code Translation (C C)
• Reverse Engineering
• Program Structure Improvement
• Program Modularization
• Data Re-Engineering

3
Re-Engineering Issues

• The quality of the software to be re-engineered
• The tool support available for re-engineering
• The extent of data conversion required
• The availability of expert staff
• ?? Microsoft Window??

4
Reverse Engineering

• Definition
• The Process of analyzing software with the
  objective of recovering its design and
  specification
• Help Engineers to understand a program before
  reorganizing its structure

5
Realism of Reverse Engineering
BCB6.0(???)
BCB 6.0(???)

Key Generator
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??????????

1. ?????????????
2. ??????????????????,??hex editor????,????????????
3. ????????????????????????(???)

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???????????

• CALL -- ?? function
• JNZ -- jump if not zero
• JZ -- jump if zero
• CMP -- ??

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Demo
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??????????,????????????
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Reference

• Heko????http//thunder.prohosting.com/heco/

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Merry Christmas and Happy New Year
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?SoftICE????Reverse-Engineering

• ??? ???

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???SoftICE?

• SoftICE Driver Suite ?????????Windows????????????
  ?? ???
• SoftICE Driver Suite?? DriverAgent-?????????????
  ??VtoolsD-??Windows?VxDs????? DriverWorks-???????
  ??????????????SoftICE-??????????????????

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NuMega SoftICE

• ??
• 1.??Internet??????,?????????????????????
• 2.?? Windows Millennium Edition,Windows
  NT,Windows 95,Windows98 ? Windows
  2000,????Windows ????????????????????? ?????????
• 3.??Pentium, Pentium Pro, Pentium
  III???????????????,?? ????SMP(SoftICE Windows
  NT)???Intel???????(APIC)?????8 ?CPU?
• 4.??Microsoft Kernel Debug extensions?

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SoftICE???
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SoftICE
Registers ? Flags  ? R ??? ?????? register ??
Data Window ? E ???, D ?? ?????????
Code Window ? A ???, U ?? ???????, ? mov eax, ebx ???
Command Window ? DOS?? ???? ????
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??HOTKEY

• F1 - Help F5 - RUN F8 - Trace (into call) F10
  - Trace (not into call) F12 - RET

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Example 1

• 137C0151       CMP BYTE PTR 14AC,00 
  137C0156       JNZ  015C  137C0159       CALL
  1A43  137C015C       MOV  AL,9
• ?????????????14AC??00,???????????????
• ??1??????????????????00 ,??????,??????2????,??????
  ???4?(015C) ?????,??????2?,???3?

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Example 1

• ??2??????,?? JZ 015C????????????????
• ?????? JMP 015C,???1??????????????3?
• ????????? JMP 015C
• ??1??? MOV BYTE PTR 14AC, 01 ,??2??? JMP 015C

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Example 2(Winzip32 v6.3)

• 00409D89    call 004096EA  00409D8E    test eax,
  eax  00409D90    jne 00409DD3  00409D92    call
  00409F9C
• ? 1 ?. ?? call ????????,????? eax ?  1 ? 0
• ? 2 ?. test eax, eax ??? eax ?? 0
• ? 3 ??? eax ? 0 ??,???? 4 ??? call?? eax ?? 0
  ??,??? 00409DD3