Lantronix Devices Authentication Bypass Vulnerability (Jun 2018) - Active Check

# SPDX-FileCopyrightText: 2018 Greenbone AG
# 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("1.3.6.1.4.1.25623.1.0.107328");
  script_version("2026-06-30T06:56:06+0000");
  script_tag(name:"last_modification", value:"2026-06-30 06:56:06 +0000 (Tue, 30 Jun 2026)");
  script_tag(name:"creation_date", value:"2018-07-12 13:43:57 +0200 (Thu, 12 Jul 2018)");
  script_tag(name:"cvss_base", value:"10.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:C/I:C/A:C");
  script_tag(name:"severity_vector", value:"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2019-10-03 00:03:00 +0000 (Thu, 03 Oct 2019)");

  script_tag(name:"qod_type", value:"remote_vul");

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

  script_cve_id("CVE-2018-12925");

  script_name("Lantronix Devices Authentication Bypass Vulnerability (Jun 2018) - Active Check");

  script_category(ACT_ATTACK);

  script_copyright("Copyright (C) 2018 Greenbone AG");
  script_family("Gain a shell remotely");
  script_dependencies("gb_lantronix_device_consolidation.nasl",
                      "gb_default_credentials_options.nasl");
  script_mandatory_keys("lantronix_device/telnet/detected");
  script_require_ports("Services/telnet", 9999);
  script_exclude_keys("default_credentials/disable_default_account_checks");

  script_xref(name:"URL", value:"https://www.seebug.org/vuldb/ssvid-97375");

  script_tag(name:"summary", value:"Lantronix devices do not require a password for Telnet
  access.");

  script_tag(name:"vuldetect", value:"Sends a crafted Telnet request and checks if the target device
  is vulnerable.");

  script_tag(name:"impact", value:"If not configured manually the device has no password
  authentication enabled by default. Attackers can gain access, gather information about the
  internal network and try to elevate their privileges.");

  script_tag(name:"affected", value:"Lantronix devices with Telnet access enabled.");

  script_tag(name:"solution", value:"Consult the documentation of your device to set a proper
  username/password combination and/or restrict remote Telnet access.");

  exit(0);
}

if(get_kb_item("default_credentials/disable_default_account_checks"))
  exit(0);

include("host_details.inc");
include("telnet_func.inc");

port = get_kb_item( "lantronix_device/telnet/port" );
username = "login";

if( ! get_kb_item( "lantronix_device/telnet/" + port + "/access" ) ) {

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

  res = recv( socket:soc, length:2048, timeout:10 );

  if( res && "prompt for assistance" >< res && "Username>" >< res ) {
    send( socket:soc, data:username + '\r\n' );
    res = recv( socket:soc, length:2048, timeout:10 );

    if( res && res =~ "Local_[^>]+>" ) {
      vuln = TRUE;
      set_kb_item( name:"lantronix_device/telnet/" + port + "/access", value:TRUE );
    }
  }

  telnet_close_socket( socket:soc, data:res );
}

else {
  vuln = TRUE;
}

if( vuln ) {
  report = "It was possible to gain Telnet access with username '" + username + "' and no password.";
  security_message( port:port, data:report );
  exit( 0 );
}

exit( 99 );