SSL/TLS: Report Perfect Forward Secrecy (PFS) Cipher Suites

# SPDX-FileCopyrightText: 2014 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("1.3.6.1.4.1.25623.1.0.105018");
  script_version("2026-03-13T05:54:58+0000");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:N");
  script_tag(name:"cvss_base", value:"0.0");
  script_tag(name:"last_modification", value:"2026-03-13 05:54:58 +0000 (Fri, 13 Mar 2026)");
  script_tag(name:"creation_date", value:"2014-05-06 14:16:10 +0100 (Tue, 06 May 2014)");
  script_name("SSL/TLS: Report Perfect Forward Secrecy (PFS) Cipher Suites");
  script_category(ACT_GATHER_INFO);
  script_family("SSL and TLS");
  script_copyright("Copyright (C) 2014 Greenbone AG");
  script_dependencies("gb_ssl_tls_ciphers_gathering.nasl");
  script_mandatory_keys("ssl_tls/ciphers/supported_ciphers", "ssl_tls/port");

  script_tag(name:"summary", value:"This routine reports all SSL/TLS cipher suites accepted by a
  service which are supporting Perfect Forward Secrecy (PFS).");

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

  exit(0);
}

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

cipherText = "Cipher suites supporting Perfect Forward Secrecy (PFS) are accepted by this service via the";

if( ! port = tls_ssl_get_port() )
  exit( 0 );

if( ! sup_ssl = tls_get_supported_kb_versions( port:port ) )
  exit( 0 );

# In theory PFS is supported since SSLv3
if( "SSLv3" >< sup_ssl ) {

  sslv3CipherList = tls_get_supported_kb_ciphers( port:port, version:"sslv3" );

  if( ! isnull( sslv3CipherList ) ) {

    # Sort to not report changes on delta reports if just the order is different
    sslv3CipherList = sort( sslv3CipherList );

    foreach sslv3Cipher( sslv3CipherList ) {
      if( egrep( pattern:'^TLS_(EC)?DHE_', string:sslv3Cipher ) ) {
        sslv3Pfs = TRUE;
        sslv3tmpReport += sslv3Cipher + '\n';
      }
    }

    if( sslv3Pfs ) {
      report += cipherText + ' SSLv3 protocol:\n\n';
      report += sslv3tmpReport;
      report += '\n';
    }
  }
}

if( "TLSv1.0" >< sup_ssl ) {

  tlsv1_0CipherList = tls_get_supported_kb_ciphers( port:port, version:"tlsv1" );

  if( ! isnull( tlsv1_0CipherList ) ) {

    # Sort to not report changes on delta reports if just the order is different
    tlsv1_0CipherList = sort( tlsv1_0CipherList );

    foreach tlsv1_0Cipher( tlsv1_0CipherList ) {
      if( egrep( pattern:'^TLS_(EC)?DHE_', string:tlsv1_0Cipher ) ) {
        tlsv1_0Pfs = TRUE;
        tlsv1_0tmpReport += tlsv1_0Cipher + '\n';
      }
    }

    if( tlsv1_0Pfs ) {
      report += cipherText + ' TLSv1.0 protocol:\n\n';
      report += tlsv1_0tmpReport;
      report += '\n';
    }
  }
}

if( "TLSv1.1" >< sup_ssl ) {

  tlsv1_1CipherList = tls_get_supported_kb_ciphers( port:port, version:"tlsv1_1" );

  if( ! isnull( tlsv1_1CipherList ) ) {

    # Sort to not report changes on delta reports if just the order is different
    tlsv1_1CipherList = sort( tlsv1_1CipherList );

    foreach tlsv1_1Cipher( tlsv1_1CipherList ) {
      if( egrep( pattern:'^TLS_(EC)?DHE_', string:tlsv1_1Cipher ) ) {
        tlsv1_1Pfs = TRUE;
        tlsv1_1tmpReport += tlsv1_1Cipher + '\n';
      }
    }

    if( tlsv1_1Pfs ) {
      report += cipherText + ' TLSv1.1 protocol:\n\n';
      report += tlsv1_1tmpReport;
      report += '\n';
    }
  }
}

if( "TLSv1.2" >< sup_ssl ) {

  tlsv1_2CipherList = tls_get_supported_kb_ciphers( port:port, version:"tlsv1_2" );

  if( ! isnull( tlsv1_2CipherList ) ) {

    # Sort to not report changes on delta reports if just the order is different
    tlsv1_2CipherList = sort( tlsv1_2CipherList );

    foreach tlsv1_2Cipher( tlsv1_2CipherList ) {
      if( egrep( pattern:'^TLS_(EC)?DHE_', string:tlsv1_2Cipher ) ) {
        tlsv1_2Pfs = TRUE;
        tlsv1_2tmpReport += tlsv1_2Cipher + '\n';
      }
    }

    if( tlsv1_2Pfs ) {
      report += cipherText + ' TLSv1.2 protocol:\n\n';
      report += tlsv1_2tmpReport;
      report += '\n';
    }
  }
}

# TLS 1.3 separate the cipher suite from the key exchange handshake.
# Every Key Exchange mechanism in TLS 1.3 is of type DHE, but we don't
# currently collect key exchange mechanisms.
if( "TLSv1.3" >< sup_ssl ) {

  tlsv1_3CipherList = tls_get_supported_kb_ciphers( port:port, version:"tlsv1_3" );

  if( ! isnull( tlsv1_3CipherList ) ) {

    # Sort to not report changes on delta reports if just the order is different
    tlsv1_3CipherList = sort( tlsv1_3CipherList );

    foreach tlsv1_3Cipher( tlsv1_3CipherList ) {
      tlsv1_3tmpReport += tlsv1_3Cipher + '\n';
    }

    report += cipherText + ' TLSv1.3 protocol:\n\n';
    report += tlsv1_3tmpReport;
    report += '\n';
  }
}

if( report ) {

  # nb:
  # - Store the reference from this one to gb_ssl_tls_ciphers_report.nasl to show a cross-reference within the
  #   reports
  # - We don't want to use get_app_* functions as we're only interested in the cross-reference here
  register_host_detail( name:"detected_by", value:"1.3.6.1.4.1.25623.1.0.802067" ); # gb_ssl_tls_ciphers_report.nasl
  register_host_detail( name:"detected_at", value:port + "/tcp" );

  log_message( port:port, data:report );
  exit( 0 );
} else {
  set_kb_item( name:"SSL/PFS/no_ciphers", value:TRUE );
  set_kb_item( name:"SSL/PFS/no_ciphers/port", value:port );
  exit( 0 );
}