Palo Alto PAN-OS Unauthenticated Buffer Overflow (PAN-SA-2016-0005) - Active Check

# SPDX-FileCopyrightText: 2016 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

CPE = "cpe:/o:paloaltonetworks:pan-os";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.105627");
  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_version("2024-06-28T15:38:46+0000");
  script_cve_id("CVE-2016-3657");
  script_name("Palo Alto PAN-OS Unauthenticated Buffer Overflow (PAN-SA-2016-0005) - Active Check");

  script_xref(name:"URL", value:"https://security.paloaltonetworks.com/CVE-2016-3657");

  script_tag(name:"summary", value:"When a PAN-OS device is configured as a GlobalProtect portal, a
  vulnerability exists where an improper handling of a buffer involved in the processing of SSL VPN
  requests can result in device crash and possible remote code execution (RCE).");

  script_tag(name:"vuldetect", value:"Send a special crafted HTTP POST request and check the response.");
  script_tag(name:"solution", value:"Update to PAN-OS releases 5.0.18, 6.0.13, 6.1.10 and 7.0.5 and newer");

  script_tag(name:"impact", value:"An attacker with network access to the vulnerable GlobalProtect portal may be able to perform a denial-of-service (DoS)
  attack on the device, and may be able to perform remote code execution on the affected device.");

  script_tag(name:"affected", value:"PAN-OS releases 5.0.17, 6.0.12, 6.1.9, 7.0.4 and prior");
  script_tag(name:"solution_type", value:"VendorFix");

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

  script_tag(name:"last_modification", value:"2024-06-28 15:38:46 +0000 (Fri, 28 Jun 2024)");
  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:"2020-02-17 16:15:00 +0000 (Mon, 17 Feb 2020)");
  script_tag(name:"creation_date", value:"2016-04-29 10:43:26 +0200 (Fri, 29 Apr 2016)");
  script_category(ACT_ATTACK);
  script_family("Web application abuses");
  script_copyright("Copyright (C) 2016 Greenbone AG");
  script_dependencies("gb_paloalto_panos_consolidation.nasl");
  script_mandatory_keys("palo_alto/http/detected");
  script_require_ports("Services/www", 443);

  exit(0);
}

include("http_func.inc");
include("http_keepalive.inc");
include("host_details.inc");
include("misc_func.inc");

if( ! port = get_app_port( cpe:CPE, service:"www" ) )
  exit( 0 );

if( ! dir  = get_app_location( cpe:CPE, port:port ) )
  exit( 0 );

if( dir == "/" )
  dir = "";

url = dir + "/global-protect/login.esp";
req = http_get( item:url, port:port );
buf = http_keepalive_send_recv( port:port, data:req, bodyonly:FALSE );

if( buf =~ "^HTTP/1\.[01] 404" ) exit( 99 );

user = crap( data:"X", length:500 );

vt_strings = get_vt_strings();
password = vt_strings["default"];

data = 'prot=https%3A' +
       '&server=' + get_host_ip() +
       '&inputStr=' +
       '&action=getsoftware' +
       '&user=' + user +
       '&passwd=' + password +
       '&ok=Login';

req = http_post_put_req( port:port,
                         url:url,
                         data:data,
                         add_headers:make_array( "Content-Type", "application/x-www-form-urlencoded" )
                       );

buf = http_keepalive_send_recv( port:port, data:req, bodyonly:FALSE );
if( buf !~ "^HTTP/1\.[01] 512" ) exit( 99 );

# It seems that the check for "512 Custom error" is enough to detect vulnerable hosts.
# But to be sure check also for different response in "respMsg"
#
# Vulnerable:
# var respMsg = "Authentication failed: Invalid username or password ";
# var respMsg = "Authentication failed: ";
#
# Fixed:
# var respMsg = "invalid user inputs";

lines = split( buf );
foreach line ( lines )
{
  if( "var respMsg" >< line )
  {
    if( "Authentication failed:" >< line )
    {
      VULN = TRUE;
      break;
    }
  }
}

if( VULN ) {
  report = http_report_vuln_url( port:port, url:url );
  security_message( port:port, data:report );
  exit( 0 );
}

exit( 99 );