Lucene search

K
nessusThis script is Copyright (C) 2024 and is owned by Tenable, Inc. or an Affiliate thereof.AL2023_ALAS2023-2024-651.NASL
HistoryJul 22, 2024 - 12:00 a.m.

Amazon Linux 2023 : openssh, openssh-clients, openssh-keycat (ALAS2023-2024-651)

2024-07-2200:00:00
This script is Copyright (C) 2024 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
7
amazon linux 2023
openssh
vulnerability
signal handler race
alas2023-2024-651
tenable
cve-2024-6409
sshd server
cleanup exit

CVSS3

8.1

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

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

AI Score

8.3

Confidence

High

EPSS

0.715

Percentile

98.1%

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2024-651 advisory.

A signal handler race condition vulnerability was found in OpenSSH's server (sshd), where a client does     not authenticate within LoginGraceTime seconds (120 by default, 600 in old OpenSSH versions), then sshd's     SIGALRM handler is called asynchronously. However, this signal handler calls various functions that are     not async-signal-safe, for example, syslog(). This issue leaves it vulnerable to a signal handler race     condition on the cleanup_exit() function, which introduces the same vulnerability as CVE-2024-6387 in the     unprivileged child of the SSHD server. (CVE-2024-6409)

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 2023 Security Advisory ALAS2023-2024-651.
##

include('compat.inc');

if (description)
{
  script_id(202916);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/07/22");

  script_cve_id("CVE-2024-6409");
  script_xref(name:"IAVA", value:"2024-A-0375");

  script_name(english:"Amazon Linux 2023 : openssh, openssh-clients, openssh-keycat (ALAS2023-2024-651)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2023 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2024-651 advisory.

    A signal handler race condition vulnerability was found in OpenSSH's server (sshd), where a client does
    not authenticate within LoginGraceTime seconds (120 by default, 600 in old OpenSSH versions), then sshd's
    SIGALRM handler is called asynchronously. However, this signal handler calls various functions that are
    not async-signal-safe, for example, syslog(). This issue leaves it vulnerable to a signal handler race
    condition on the cleanup_exit() function, which introduces the same vulnerability as CVE-2024-6387 in the
    unprivileged child of the SSHD server. (CVE-2024-6409)

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/AL2023/ALAS-2024-651.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2024-6409.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/faqs.html");
  script_set_attribute(attribute:"solution", value:
"Run 'dnf update openssh --releasever 2023.5.20240722' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:N/C:P/I:P/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:L/I:L/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-2024-6409");

  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:"2024/07/03");
  script_set_attribute(attribute:"patch_publication_date", value:"2024/07/18");
  script_set_attribute(attribute:"plugin_publication_date", value:"2024/07/22");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-clients");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-clients-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-debugsource");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-keycat");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-keycat-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-server");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:openssh-server-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:pam_ssh_agent_auth");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:pam_ssh_agent_auth-debuginfo");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2023");
  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) 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 != "-2023")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2023", "Amazon Linux " + os_ver);
}

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

var pkgs = [
    {'reference':'openssh-8.7p1-8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-8.7p1-8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-clients-8.7p1-8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-clients-8.7p1-8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-clients-debuginfo-8.7p1-8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-clients-debuginfo-8.7p1-8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-debuginfo-8.7p1-8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-debuginfo-8.7p1-8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-debugsource-8.7p1-8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-debugsource-8.7p1-8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-keycat-8.7p1-8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-keycat-8.7p1-8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-keycat-debuginfo-8.7p1-8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-keycat-debuginfo-8.7p1-8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-server-8.7p1-8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-server-8.7p1-8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-server-debuginfo-8.7p1-8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'openssh-server-debuginfo-8.7p1-8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE, 'allowmaj':TRUE},
    {'reference':'pam_ssh_agent_auth-0.10.4-4.8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'pam_ssh_agent_auth-0.10.4-4.8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'pam_ssh_agent_auth-debuginfo-0.10.4-4.8.amzn2023.0.12', 'cpu':'aarch64', 'release':'AL-2023', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'pam_ssh_agent_auth-debuginfo-0.10.4-4.8.amzn2023.0.12', 'cpu':'x86_64', 'release':'AL-2023', '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_WARNING,
      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, "openssh / openssh-clients / openssh-clients-debuginfo / etc");
}
VendorProductVersionCPE
amazonlinuxopenssh-clientsp-cpe:/a:amazon:linux:openssh-clients
amazonlinuxopenssh-clients-debuginfop-cpe:/a:amazon:linux:openssh-clients-debuginfo
amazonlinuxopenssh-keycatp-cpe:/a:amazon:linux:openssh-keycat
amazonlinuxpam_ssh_agent_authp-cpe:/a:amazon:linux:pam_ssh_agent_auth
amazonlinuxopenssh-debugsourcep-cpe:/a:amazon:linux:openssh-debugsource
amazonlinuxopenssh-keycat-debuginfop-cpe:/a:amazon:linux:openssh-keycat-debuginfo
amazonlinuxopenssh-serverp-cpe:/a:amazon:linux:openssh-server
amazonlinuxopenssh-server-debuginfop-cpe:/a:amazon:linux:openssh-server-debuginfo
amazonlinuxpam_ssh_agent_auth-debuginfop-cpe:/a:amazon:linux:pam_ssh_agent_auth-debuginfo
amazonlinuxopensshp-cpe:/a:amazon:linux:openssh
Rows per page:
1-10 of 121

CVSS3

8.1

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

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

AI Score

8.3

Confidence

High

EPSS

0.715

Percentile

98.1%