Wednesday, January 24, 2024

Vlang Binary Debugging

Why vlang? V is a featured, productive, safe and confortable language highly compatible with c, that generates neat binaries with c-speed, the decompilation also seems quite clear as c code.
https://vlang.io/

After open the binary with radare in debug mode "-d" we proceed to do the binary recursive analysis with "aaaa" the more a's the more deep analys.



The function names are modified when the binary is crafted, if we have a function named hello in a module named main we will have the symbol main__hello, but we can locate them quicly thanks to radare's grep done with "~" token in this case applied to the "afl" command which lists all the symbols.


Being in debug mode we can use "d*" commands, for example "db" for breakpointing the function and then "dc" to start or continue execution.


Let's dissasemble the function with "pD" command, it also displays the function variables and arguments as well, note also the xref "call xref from main"


Let's take a look to the function arguments, radare detect's this three 64bits registers used on the function.


Actually the function parameter is rsi that contains a testing html to test the href extraction algorithm.


The string structure is quite simple and it's plenty of implemented methods.




With F8 we can step over the code as we were in ollydbg on linux.


Note the rip marker sliding into the code.


We can recognize the aray creations, and the s.index_after() function used to find substrings since a specific position.


If we take a look de dissasembly we sill see quite a few calls to tos3() functions.
Those functions are involved in string initialization, and implements safety checks.

  • tos(string, len)
  • tos2(byteptr)
  • tos3(charptr)

In this case I have a crash in my V code and I want to know what is crashing, just continue the execution with "dc" and see what poits the rip register.



In visual mode "V" we can see previous instructions to figure out the arguments and state.


We've located the crash on the substring operation which is something like "s2 := s1[a..b]" probably one of the arguments of the substring is out of bounds but luckily the V language has safety checks and is a controlled termination:



Switching the basic block view "space" we can see the execution flow, in this case we know the loops and branches because we have the code but this view also we can see the tos3 parameter "href=" which is useful to locate the position on the code.



When it reach the substr, we can see the parameters with "tab" command.



Looking the implementation the radare parameter calculation is quite exact.


Let's check the param values:


so the indexes are from 0x0e to 0x24 which are inside the buffer, lets continue to next iteration,
if we set a breakpoint and check every iteration, on latest iteration before the crash we have the values 0x2c to 0x70 with overflows the buffer and produces a controlled termination of the v compiled process.





More articles


  1. Hacker Tool Kit
  2. Pentest Tools Apk
  3. Pentest Automation Tools
  4. Hacking App
  5. Hack Tools For Games
  6. Hack Tools Download
  7. Pentest Tools Review
  8. Hak5 Tools
  9. Hak5 Tools
  10. Hacking App
  11. Pentest Tools For Windows
  12. Pentest Tools Website Vulnerability
  13. Hacker Tools Apk Download
  14. Best Hacking Tools 2020
  15. Pentest Tools For Mac
  16. Hacker Tools Linux
  17. Pentest Tools Url Fuzzer
  18. Pentest Tools Kali Linux
  19. Hacker Tools Github
  20. Pentest Tools List
  21. Termux Hacking Tools 2019
  22. Usb Pentest Tools
  23. Hacker Tools Github
  24. Pentest Tools For Mac
  25. Pentest Tools Bluekeep
  26. Hacking Tools Usb
  27. Pentest Tools For Android
  28. Hacker Tools Software
  29. Hacking Tools For Games
  30. Hacks And Tools
  31. Pentest Recon Tools
  32. Pentest Tools Android
  33. Install Pentest Tools Ubuntu
  34. Hack App
  35. Install Pentest Tools Ubuntu
  36. Hacker Tools Github
  37. Hack Tools For Windows
  38. How To Install Pentest Tools In Ubuntu
  39. How To Hack
  40. Pentest Tools Website Vulnerability
  41. Hacker Security Tools
  42. Underground Hacker Sites
  43. Hack And Tools
  44. Pentest Tools Url Fuzzer
  45. Hackers Toolbox
  46. Hacking Tools Usb
  47. How To Make Hacking Tools
  48. Hack And Tools
  49. Wifi Hacker Tools For Windows
  50. Pentest Tools Framework
  51. Hacker Tools Apk
  52. Hacker Tools For Ios
  53. Hacker Tools Github
  54. Hacking Tools For Windows
  55. Hack Apps
  56. Nsa Hack Tools
  57. Hacker Tools Free Download
  58. Pentest Tools Open Source
  59. Hack Tools Download
  60. Hack Tools For Windows
  61. Hacking Tools Github
  62. Hacking Tools For Mac
  63. Wifi Hacker Tools For Windows
  64. Best Hacking Tools 2019
  65. Hak5 Tools
  66. Hacker Tools Hardware
  67. Black Hat Hacker Tools
  68. Hack Tools For Windows
  69. Hack Tools Online
  70. How To Make Hacking Tools
  71. Pentest Tools For Mac
  72. Hacker Tools Online
  73. Best Hacking Tools 2020
  74. Pentest Tools Github
  75. Hacks And Tools
  76. Pentest Tools Website
  77. Pentest Tools Framework
  78. Hacker Tools For Pc
  79. Hacker Hardware Tools
  80. Hak5 Tools
  81. Hacks And Tools
  82. Hacking Tools For Kali Linux
  83. Hacking Tools Windows
  84. Hacker Tools Software
  85. Hack Tools For Games
  86. Hacking Tools For Games
  87. Hacking Tools For Mac
  88. Github Hacking Tools
  89. Pentest Tools Online
  90. Hack Tools For Ubuntu
  91. Pentest Tools For Mac
  92. What Are Hacking Tools
  93. Hacking Tools For Windows 7
  94. Game Hacking
  95. Hack Tools Download
  96. Best Pentesting Tools 2018
  97. Hacker Tools 2020
  98. Hacker
  99. Nsa Hack Tools
  100. Hacking Tools For Pc
  101. Github Hacking Tools
  102. Hack Tools Pc
  103. Hacker Security Tools
  104. Pentest Tools Windows
  105. Hacking Tools Mac
  106. Hacking Tools And Software
  107. Pentest Tools Nmap
  108. Hacking Tools For Mac
  109. Hacking Tools Windows 10
  110. Pentest Tools Tcp Port Scanner
  111. Hacks And Tools
  112. Pentest Tools Website Vulnerability
  113. Hackers Toolbox
  114. Hacking Tools Kit
  115. Hacking Tools Pc
  116. Pentest Tools Download

No comments:

Post a Comment