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nessusThis script is Copyright (C) 2023 and is owned by Tenable, Inc. or an Affiliate thereof.AL2_ALAS-2023-1935.NASL
HistoryFeb 08, 2023 - 12:00 a.m.

Amazon Linux 2 : openssl (ALAS-2023-1935)

2023-02-0800:00:00
This script is Copyright (C) 2023 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
70
openssl
rsa decryption
time-based attack
rsa padding
bio_new_ndef
use-after-free
type confusion x.400
generalname
crl checking

EPSS

0.006

Percentile

79.4%

The version of openssl installed on the remote host is prior to 1.0.2k-24. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2023-1935 advisory.

  • A timing based side channel exists in the OpenSSL RSA Decryption implementation which could be sufficient to recover a plaintext across a network in a Bleichenbacher style attack. To achieve a successful decryption an attacker would have to be able to send a very large number of trial messages for decryption.
    The vulnerability affects all RSA padding modes: PKCS#1 v1.5, RSA-OEAP and RSASVE. For example, in a TLS connection, RSA is commonly used by a client to send an encrypted pre-master secret to the server. An attacker that had observed a genuine connection between a client and a server could use this flaw to send trial messages to the server and record the time taken to process them. After a sufficiently large number of messages the attacker could recover the pre-master secret used for the original connection and thus be able to decrypt the application data sent over that connection. (CVE-2022-4304)

  • The public API function BIO_new_NDEF is a helper function used for streaming ASN.1 data via a BIO. It is primarily used internally to OpenSSL to support the SMIME, CMS and PKCS7 streaming capabilities, but may also be called directly by end user applications. The function receives a BIO from the caller, prepends a new BIO_f_asn1 filter BIO onto the front of it to form a BIO chain, and then returns the new head of the BIO chain to the caller. Under certain conditions, for example if a CMS recipient public key is invalid, the new filter BIO is freed and the function returns a NULL result indicating a failure. However, in this case, the BIO chain is not properly cleaned up and the BIO passed by the caller still retains internal pointers to the previously freed filter BIO. If the caller then goes on to call BIO_pop() on the BIO then a use-after-free will occur. This will most likely result in a crash. This scenario occurs directly in the internal function B64_write_ASN1() which may cause BIO_new_NDEF() to be called and will subsequently call BIO_pop() on the BIO. This internal function is in turn called by the public API functions PEM_write_bio_ASN1_stream, PEM_write_bio_CMS_stream, PEM_write_bio_PKCS7_stream, SMIME_write_ASN1, SMIME_write_CMS and SMIME_write_PKCS7. Other public API functions that may be impacted by this include i2d_ASN1_bio_stream, BIO_new_CMS, BIO_new_PKCS7, i2d_CMS_bio_stream and i2d_PKCS7_bio_stream. The OpenSSL cms and smime command line applications are similarly affected. (CVE-2023-0215)

  • There is a type confusion vulnerability relating to X.400 address processing inside an X.509 GeneralName.
    X.400 addresses were parsed as an ASN1_STRING but the public structure definition for GENERAL_NAME incorrectly specified the type of the x400Address field as ASN1_TYPE. This field is subsequently interpreted by the OpenSSL function GENERAL_NAME_cmp as an ASN1_TYPE rather than an ASN1_STRING. When CRL checking is enabled (i.e. the application sets the X509_V_FLAG_CRL_CHECK flag), this vulnerability may allow an attacker to pass arbitrary pointers to a memcmp call, enabling them to read memory contents or enact a denial of service. In most cases, the attack requires the attacker to provide both the certificate chain and CRL, neither of which need to have a valid signature. If the attacker only controls one of these inputs, the other input must already contain an X.400 address as a CRL distribution point, which is uncommon. As such, this vulnerability is most likely to only affect applications which have implemented their own functionality for retrieving CRLs over a network. (CVE-2023-0286)

Note that Nessus has not tested for these issues but has instead relied only on the application’s self-reported version number.

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALAS-2023-1935.
##

include('compat.inc');

if (description)
{
  script_id(171226);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/09/15");

  script_cve_id("CVE-2022-4304", "CVE-2023-0215", "CVE-2023-0286");
  script_xref(name:"IAVA", value:"2022-A-0518-S");

  script_name(english:"Amazon Linux 2 : openssl (ALAS-2023-1935)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of openssl installed on the remote host is prior to 1.0.2k-24. It is, therefore, affected by multiple
vulnerabilities as referenced in the ALAS2-2023-1935 advisory.

  - A timing based side channel exists in the OpenSSL RSA Decryption implementation which could be sufficient
    to recover a plaintext across a network in a Bleichenbacher style attack. To achieve a successful
    decryption an attacker would have to be able to send a very large number of trial messages for decryption.
    The vulnerability affects all RSA padding modes: PKCS#1 v1.5, RSA-OEAP and RSASVE. For example, in a TLS
    connection, RSA is commonly used by a client to send an encrypted pre-master secret to the server. An
    attacker that had observed a genuine connection between a client and a server could use this flaw to send
    trial messages to the server and record the time taken to process them. After a sufficiently large number
    of messages the attacker could recover the pre-master secret used for the original connection and thus be
    able to decrypt the application data sent over that connection. (CVE-2022-4304)

  - The public API function BIO_new_NDEF is a helper function used for streaming ASN.1 data via a BIO. It is
    primarily used internally to OpenSSL to support the SMIME, CMS and PKCS7 streaming capabilities, but may
    also be called directly by end user applications. The function receives a BIO from the caller, prepends a
    new BIO_f_asn1 filter BIO onto the front of it to form a BIO chain, and then returns the new head of the
    BIO chain to the caller. Under certain conditions, for example if a CMS recipient public key is invalid,
    the new filter BIO is freed and the function returns a NULL result indicating a failure. However, in this
    case, the BIO chain is not properly cleaned up and the BIO passed by the caller still retains internal
    pointers to the previously freed filter BIO. If the caller then goes on to call BIO_pop() on the BIO then
    a use-after-free will occur. This will most likely result in a crash. This scenario occurs directly in the
    internal function B64_write_ASN1() which may cause BIO_new_NDEF() to be called and will subsequently call
    BIO_pop() on the BIO. This internal function is in turn called by the public API functions
    PEM_write_bio_ASN1_stream, PEM_write_bio_CMS_stream, PEM_write_bio_PKCS7_stream, SMIME_write_ASN1,
    SMIME_write_CMS and SMIME_write_PKCS7. Other public API functions that may be impacted by this include
    i2d_ASN1_bio_stream, BIO_new_CMS, BIO_new_PKCS7, i2d_CMS_bio_stream and i2d_PKCS7_bio_stream. The OpenSSL
    cms and smime command line applications are similarly affected. (CVE-2023-0215)

  - There is a type confusion vulnerability relating to X.400 address processing inside an X.509 GeneralName.
    X.400 addresses were parsed as an ASN1_STRING but the public structure definition for GENERAL_NAME
    incorrectly specified the type of the x400Address field as ASN1_TYPE. This field is subsequently
    interpreted by the OpenSSL function GENERAL_NAME_cmp as an ASN1_TYPE rather than an ASN1_STRING. When CRL
    checking is enabled (i.e. the application sets the X509_V_FLAG_CRL_CHECK flag), this vulnerability may
    allow an attacker to pass arbitrary pointers to a memcmp call, enabling them to read memory contents or
    enact a denial of service. In most cases, the attack requires the attacker to provide both the certificate
    chain and CRL, neither of which need to have a valid signature. If the attacker only controls one of these
    inputs, the other input must already contain an X.400 address as a CRL distribution point, which is
    uncommon. As such, this vulnerability is most likely to only affect applications which have implemented
    their own functionality for retrieving CRLs over a network. (CVE-2023-0286)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/../../faqs.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/AL2/ALAS-2023-1935.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2022-4304.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2023-0215.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2023-0286.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update openssl' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:N/C:C/I:N/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2023-0286");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2022/12/15");
  script_set_attribute(attribute:"patch_publication_date", value:"2023/02/03");
  script_set_attribute(attribute:"plugin_publication_date", value:"2023/02/08");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl-libs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl-perl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssl-static");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Amazon Linux Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/AmazonLinux/release", "Host/AmazonLinux/rpm-list");

  exit(0);
}

include("rpm.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);

var alas_release = get_kb_item("Host/AmazonLinux/release");
if (isnull(alas_release) || !strlen(alas_release)) audit(AUDIT_OS_NOT, "Amazon Linux");
var os_ver = pregmatch(pattern: "^AL(A|\d+|-\d+)", string:alas_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
os_ver = os_ver[1];
if (os_ver != "2")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2", "Amazon Linux " + os_ver);
}

if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

var pkgs = [
    {'reference':'openssl-1.0.2k-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-1.0.2k-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-1.0.2k-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-debuginfo-1.0.2k-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-debuginfo-1.0.2k-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-debuginfo-1.0.2k-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-devel-1.0.2k-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-devel-1.0.2k-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-devel-1.0.2k-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-libs-1.0.2k-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-libs-1.0.2k-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-libs-1.0.2k-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-perl-1.0.2k-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-perl-1.0.2k-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-perl-1.0.2k-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-static-1.0.2k-24.amzn2.0.6', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-static-1.0.2k-24.amzn2.0.6', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-static-1.0.2k-24.amzn2.0.6', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var reference = NULL;
  var _release = NULL;
  var sp = NULL;
  var _cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var epoch = NULL;
  var allowmaj = NULL;
  var exists_check = NULL;
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (!empty_or_null(package_array['release'])) _release = package_array['release'];
  if (!empty_or_null(package_array['sp'])) sp = package_array['sp'];
  if (!empty_or_null(package_array['cpu'])) _cpu = package_array['cpu'];
  if (!empty_or_null(package_array['el_string'])) el_string = package_array['el_string'];
  if (!empty_or_null(package_array['rpm_spec_vers_cmp'])) rpm_spec_vers_cmp = package_array['rpm_spec_vers_cmp'];
  if (!empty_or_null(package_array['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['exists_check'])) exists_check = package_array['exists_check'];
  if (reference && _release && (!exists_check || rpm_exists(release:_release, rpm:exists_check))) {
    if (rpm_check(release:_release, sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj)) flag++;
  }
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "openssl / openssl-debuginfo / openssl-devel / etc");
}