Amazon Linux 2 : openssl (ALAS-2024-2604)

2024-08-1700:00:00

www.tenable.com

amazon linux 2

openssl

alas-2024-2604

vulnerability

buffer overread

confidentiality

alpn

npn

tls applications

fips modules.

CVSS3

9.1

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

AI Score

7.4

Confidence

High

JSON

The version of openssl installed on the remote host is prior to 1.0.2k-24. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2024-2604 advisory.

Issue summary: Calling the OpenSSL API function SSL_select_next_proto with anempty supported client     protocols buffer may cause a crash or memory contents tobe sent to the peer.

Impact summary: A buffer overread can have a range of potential consequencessuch as unexpected application     beahviour or a crash. In particular this issuecould result in up to 255 bytes of arbitrary private data     from memory being sentto the peer leading to a loss of confidentiality. However, only applicationsthat     directly call the SSL_select_next_proto function with a 0 length list ofsupported client protocols are     affected by this issue. This would normally neverbe a valid scenario and is typically not under attacker     control but may occur byaccident in the case of a configuration or programming error in the     callingapplication.

The OpenSSL API function SSL_select_next_proto is typically used by TLSapplications that support ALPN     (Application Layer Protocol Negotiation) or NPN(Next Protocol Negotiation). NPN is older, was never     standardised andis deprecated in favour of ALPN. We believe that ALPN is significantly morewidely deployed     than NPN. The SSL_select_next_proto function accepts a list ofprotocols from the server and a list of     protocols from the client and returnsthe first protocol that appears in the server list that also appears     in theclient list. In the case of no overlap between the two lists it returns thefirst item in the client     list. In either case it will signal whether an overlapbetween the two lists was found. In the case where     SSL_select_next_proto iscalled with a zero length client list it fails to notice this condition andreturns     the memory immediately following the client list pointer (and reportsthat there was no overlap in the     lists).

This function is typically called from a server side application callback forALPN or a client side     application callback for NPN. In the case of ALPN the listof protocols supplied by the client is     guaranteed by libssl to never be zero inlength. The list of server protocols comes from the application     and should nevernormally be expected to be of zero length. In this case if theSSL_select_next_proto     function has been called as expected (with the listsupplied by the client passed in the client/client_len     parameters), then theapplication will not be vulnerable to this issue. If the application hasaccidentally     been configured with a zero length server list, and hasaccidentally passed that zero length server list in     the client/client_lenparameters, and has additionally failed to correctly handle a no overlapresponse     (which would normally result in a handshake failure in ALPN) then itwill be vulnerable to this problem.

In the case of NPN, the protocol permits the client to opportunistically selecta protocol when there is no     overlap. OpenSSL returns the first client protocolin the no overlap case in support of this. The list of     client protocols comesfrom the application and should never normally be expected to be of zero     length.However if the SSL_select_next_proto function is accidentally called with aclient_len of 0 then an     invalid memory pointer will be returned instead. If theapplication uses this output as the opportunistic     protocol then the loss ofconfidentiality will occur.

This issue has been assessed as Low severity because applications are mostlikely to be vulnerable if they     are using NPN instead of ALPN - but NPN is notwidely used. It also requires an application configuration     or programming error.Finally, this issue would not typically be under attacker control making     activeexploitation unlikely.

The FIPS modules in 3.3, 3.2, 3.1 and 3.0 are not affected by this issue.

Due to the low severity of this issue we are not issuing new releases ofOpenSSL at this time. The fix will     be included in the next releases when theybecome available. (CVE-2024-5535)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue 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-2024-2604.
##

include('compat.inc');

if (description)
{
  script_id(205731);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/17");

  script_cve_id("CVE-2024-5535");

  script_name(english:"Amazon Linux 2 : openssl (ALAS-2024-2604)");

  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 a vulnerability
as referenced in the ALAS2-2024-2604 advisory.

    Issue summary: Calling the OpenSSL API function SSL_select_next_proto with anempty supported client
    protocols buffer may cause a crash or memory contents tobe sent to the peer.

    Impact summary: A buffer overread can have a range of potential consequencessuch as unexpected application
    beahviour or a crash. In particular this issuecould result in up to 255 bytes of arbitrary private data
    from memory being sentto the peer leading to a loss of confidentiality. However, only applicationsthat
    directly call the SSL_select_next_proto function with a 0 length list ofsupported client protocols are
    affected by this issue. This would normally neverbe a valid scenario and is typically not under attacker
    control but may occur byaccident in the case of a configuration or programming error in the
    callingapplication.

    The OpenSSL API function SSL_select_next_proto is typically used by TLSapplications that support ALPN
    (Application Layer Protocol Negotiation) or NPN(Next Protocol Negotiation). NPN is older, was never
    standardised andis deprecated in favour of ALPN. We believe that ALPN is significantly morewidely deployed
    than NPN. The SSL_select_next_proto function accepts a list ofprotocols from the server and a list of
    protocols from the client and returnsthe first protocol that appears in the server list that also appears
    in theclient list. In the case of no overlap between the two lists it returns thefirst item in the client
    list. In either case it will signal whether an overlapbetween the two lists was found. In the case where
    SSL_select_next_proto iscalled with a zero length client list it fails to notice this condition andreturns
    the memory immediately following the client list pointer (and reportsthat there was no overlap in the
    lists).

    This function is typically called from a server side application callback forALPN or a client side
    application callback for NPN. In the case of ALPN the listof protocols supplied by the client is
    guaranteed by libssl to never be zero inlength. The list of server protocols comes from the application
    and should nevernormally be expected to be of zero length. In this case if theSSL_select_next_proto
    function has been called as expected (with the listsupplied by the client passed in the client/client_len
    parameters), then theapplication will not be vulnerable to this issue. If the application hasaccidentally
    been configured with a zero length server list, and hasaccidentally passed that zero length server list in
    the client/client_lenparameters, and has additionally failed to correctly handle a no overlapresponse
    (which would normally result in a handshake failure in ALPN) then itwill be vulnerable to this problem.

    In the case of NPN, the protocol permits the client to opportunistically selecta protocol when there is no
    overlap. OpenSSL returns the first client protocolin the no overlap case in support of this. The list of
    client protocols comesfrom the application and should never normally be expected to be of zero
    length.However if the SSL_select_next_proto function is accidentally called with aclient_len of 0 then an
    invalid memory pointer will be returned instead. If theapplication uses this output as the opportunistic
    protocol then the loss ofconfidentiality will occur.

    This issue has been assessed as Low severity because applications are mostlikely to be vulnerable if they
    are using NPN instead of ALPN - but NPN is notwidely used. It also requires an application configuration
    or programming error.Finally, this issue would not typically be under attacker control making
    activeexploitation unlikely.

    The FIPS modules in 3.3, 3.2, 3.1 and 3.0 are not affected by this issue.

    Due to the low severity of this issue we are not issuing new releases ofOpenSSL at this time. The fix will
    be included in the next releases when theybecome available. (CVE-2024-5535)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue 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/AL2/ALAS-2024-2604.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2024-5535.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/faqs.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update openssl' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/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:L/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-2024-5535");

  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:"2024/06/26");
  script_set_attribute(attribute:"patch_publication_date", value:"2024/08/01");
  script_set_attribute(attribute:"plugin_publication_date", value:"2024/08/17");

  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_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2024 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.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-1.0.2k-24.amzn2.0.13', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-1.0.2k-24.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-debuginfo-1.0.2k-24.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-debuginfo-1.0.2k-24.amzn2.0.13', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-debuginfo-1.0.2k-24.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-devel-1.0.2k-24.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-devel-1.0.2k-24.amzn2.0.13', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-devel-1.0.2k-24.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-libs-1.0.2k-24.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-libs-1.0.2k-24.amzn2.0.13', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-libs-1.0.2k-24.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-perl-1.0.2k-24.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-perl-1.0.2k-24.amzn2.0.13', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-perl-1.0.2k-24.amzn2.0.13', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-static-1.0.2k-24.amzn2.0.13', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-static-1.0.2k-24.amzn2.0.13', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'openssl-static-1.0.2k-24.amzn2.0.13', '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");
}