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.

Related word

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