Linux Stack Protection By Default

  
Modern gcc compiler (v9.2.0) protects the stack by default and you will notice it because instead of SIGSEGV on stack overflow you will get a SIGABRT, but it also generates coredumps.




In this case the compiler adds the variable local_10. This variable helds a canary value that is checked at the end of the function.
The memset overflows the four bytes stack variable and modifies the canary value.



The 64bits canary 0x5429851ebaf95800 can't be predicted, but in specific situations is not re-generated and can be bruteforced or in other situations can be leaked from memory for example using a format string vulnerability or an arbitrary read wihout overflowing the stack.

If the canary doesn't match, the libc function __stack_chck_fail is called and terminates the prorgam with a SIGABORT which generates a coredump, in the case of archlinux managed by systemd and are stored on "/var/lib/systemd/coredump/"


❯❯❯ ./test 
*** stack smashing detected ***: terminated
fish: './test' terminated by signal SIGABRT (Abort)

❯❯❯ sudo lz4 -d core.test.1000.c611b7caa58a4fa3bcf403e6eac95bb0.1121.1574354610000000.lz4
[sudo] password for xxxx: 
Decoding file core.test.1000.c611b7caa58a4fa3bcf403e6eac95bb0.1121.1574354610000000 
core.test.1000.c611b : decoded 249856 bytes 

 ❯❯❯ sudo gdb /home/xxxx/test core.test.1000.c611b7caa58a4fa3bcf403e6eac95bb0.1121.1574354610000000 -q 


We specify the binary and the core file as a gdb parameters. We can see only one LWP (light weight process) or linux thread, so in this case is quicker to check. First of all lets see the back trace, because in this case the execution don't terminate in the segfaulted return.




We can see on frame 5 the address were it would had returned to main if it wouldn't aborted.



Happy Idea: we can use this stack canary aborts to detect stack overflows. In Debian with prevous versions it will be exploitable depending on the compilation flags used.
And note that the canary is located as the last variable in the stack so the previous variables can be overwritten without problems.




More info
  1. Pentest Automation Tools
  2. Hack Tools
  3. Growth Hacker Tools
  4. Github Hacking Tools
  5. Hacking Tools Download
  6. Best Hacking Tools 2020
  7. Pentest Tools Online
  8. New Hacker Tools
  9. What Are Hacking Tools
  10. Kik Hack Tools
  11. Hacking Tools For Windows Free Download
  12. Best Pentesting Tools 2018
  13. Hacker Tool Kit
  14. Hacking Tools Windows 10
  15. Pentest Tools Bluekeep
  16. Pentest Tools Subdomain
  17. Pentest Tools Kali Linux
  18. Hacker Tools Free
  19. Hacking Tools Software
  20. What Are Hacking Tools
  21. Github Hacking Tools
  22. Hack Tool Apk
  23. Nsa Hack Tools
  24. Hacker Tools Apk Download
  25. How To Install Pentest Tools In Ubuntu
  26. Pentest Tools Subdomain
  27. Easy Hack Tools
  28. Best Hacking Tools 2020
  29. Hack Tools Github
  30. Android Hack Tools Github
  31. Hacking Tools Github
  32. Hacker Tools Free Download
  33. Hack Website Online Tool
  34. Hacking Apps
  35. Hack App
  36. Hack Tools For Windows
  37. Hack Tools Pc
  38. Tools 4 Hack
  39. Hacking Tools For Kali Linux
  40. Hack Tools Mac
  41. Hacking Tools For Windows Free Download
  42. Pentest Tools Url Fuzzer
  43. Kik Hack Tools
  44. Pentest Tools Open Source
  45. Hacking Tools For Games
  46. Pentest Tools
  47. What Are Hacking Tools
  48. Pentest Tools Linux
  49. Hack Tools Github
  50. Hack Tools Pc
  51. Black Hat Hacker Tools
  52. Hacker Tools Online
  53. Hacking Tools
  54. Top Pentest Tools
  55. Pentest Tools Port Scanner
  56. Pentest Tools Review
  57. Pentest Tools Url Fuzzer
  58. Pentest Tools Website
  59. Tools Used For Hacking
  60. Physical Pentest Tools
  61. Pentest Tools For Android
  62. Hack Tools Mac
  63. Hack App
  64. Underground Hacker Sites
  65. Hacker Tools For Ios
  66. Hacking Tools Name
  67. Pentest Tools Apk
  68. Pentest Tools Subdomain
  69. Pentest Tools Framework
  70. Hacker Tools Apk Download
  71. Pentest Recon Tools
  72. Nsa Hacker Tools
  73. Usb Pentest Tools
  74. Hack Rom Tools
  75. Ethical Hacker Tools
  76. Hack Tools For Windows
  77. Hacker Tools Software
  78. Hacking Tools Download
  79. Hacking Tools Mac
  80. Hackrf Tools
  81. Pentest Tools For Android
  82. Pentest Tools Find Subdomains
  83. Pentest Tools Linux
  84. Hacker Tools Mac
  85. Hacks And Tools
  86. Hacking Tools
  87. Hacking Tools For Windows Free Download
  88. Hacker Tools 2019
  89. Hack Rom Tools
  90. Hacking Tools Windows 10
  91. Hacking Tools Online
  92. Hack Rom Tools
  93. Hackrf Tools
  94. Nsa Hack Tools
  95. Hacking Tools For Windows Free Download
  96. Hack Tools Pc
  97. Hack Tools Github
  98. Pentest Tools For Mac
  99. Pentest Tools Website
  100. Pentest Box Tools Download
  101. Pentest Tools Tcp Port Scanner
  102. Best Hacking Tools 2019
  103. Hack App
  104. Pentest Tools For Windows
  105. Hacking Tools 2020
  106. Pentest Tools Find Subdomains
  107. Pentest Tools Tcp Port Scanner
  108. Hacking Tools Usb
  109. Hacker Tools 2020
  110. Hacking Tools Windows 10
  111. Hack And Tools
  112. Pentest Tools For Ubuntu
  113. Hacking Tools Hardware
  114. Hacker Techniques Tools And Incident Handling
  115. Hack Tools 2019
  116. How To Make Hacking Tools
  117. Hacker Tools
  118. Install Pentest Tools Ubuntu
  119. Hack Tools
  120. Hacker Tools Mac
  121. Pentest Box Tools Download
  122. Hacking Tools Software
  123. Hacker Tools Online
  124. Hacking Tools Pc
  125. Hacking Tools For Mac
  126. Pentest Tools For Mac
  127. Hack Tools For Ubuntu
  128. Hacking Tools 2019
  129. Android Hack Tools Github
  130. Pentest Tools For Ubuntu
  131. Wifi Hacker Tools For Windows
  132. Hacker Tools Online
  133. Hack Rom Tools
  134. Hacking Tools For Windows 7
  135. Pentest Tools Android
  136. Hacking Tools Mac
  137. Best Pentesting Tools 2018
  138. Pentest Tools Framework
  139. Pentest Tools Nmap
  140. Pentest Tools Open Source
  141. Hack Tools For Windows
  142. Hacking Tools And Software
  143. Hacking Tools For Beginners
  144. Hacking Tools For Windows
  145. Hacking Tools Software
  146. Hack Tools For Ubuntu
  147. Hacking Tools Github
  148. Pentest Tools Linux
  149. Pentest Tools
  150. Hacking Tools Download
  151. Black Hat Hacker Tools
  152. Hacker Tools Mac
  153. Free Pentest Tools For Windows
  154. Hacking Tools Software
  155. Pentest Tools Android
  156. How To Install Pentest Tools In Ubuntu
  157. Pentest Tools Url Fuzzer
  158. Best Pentesting Tools 2018
  159. Hacker Tools Windows
  160. Hacker Tools For Windows

0 comments:

Post a Comment

Subscribe to: Post Comments (Atom)