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This script is Copyright (C) 2022-2023 and is owned by Tenable, Inc. or an Affiliate thereof.AL2_ALASKERNEL-5_4-2022-016.NASL
HistoryMay 02, 2022 - 12:00 a.m.

Amazon Linux 2 : kernel (ALASKERNEL-5.4-2022-016)

2022-05-0200:00:00
This script is Copyright (C) 2022-2023 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
13

The version of kernel installed on the remote host is prior to 5.4.68-34.125. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2KERNEL-5.4-2022-016 advisory.

  • In the Linux kernel 5.0.21 and 5.3.11, mounting a crafted btrfs filesystem image, performing some operations, and then making a syncfs system call can lead to a use-after-free in try_merge_free_space in fs/btrfs/free-space-cache.c because the pointer to a left data structure can be the same as the pointer to a right data structure. (CVE-2019-19448)

  • DISPUTED In the Linux kernel 4.19.83, there is a use-after-free (read) in the debugfs_remove function in fs/debugfs/inode.c (which is used to remove a file or directory in debugfs that was previously created with a call to another debugfs function such as debugfs_create_file). NOTE: Linux kernel developers dispute this issue as not being an issue with debugfs, instead this is an issue with misuse of debugfs within blktrace. (CVE-2019-19770)

  • The VFIO PCI driver in the Linux kernel through 5.6.13 mishandles attempts to access disabled memory space. (CVE-2020-12888)

  • A memory out-of-bounds read flaw was found in the Linux kernel before 5.9-rc2 with the ext3/ext4 file system, in the way it accesses a directory with broken indexing. This flaw allows a local user to crash the system if the directory exists. The highest threat from this vulnerability is to system availability.
    (CVE-2020-14314)

  • A flaw was found in the Linux kernel before 5.9-rc4. A failure of the file system metadata validator in XFS can cause an inode with a valid, user-creatable extended attribute to be flagged as corrupt. This can lead to the filesystem being shutdown, or otherwise rendered inaccessible until it is remounted, leading to a denial of service. The highest threat from this vulnerability is to system availability.
    (CVE-2020-14385)

  • A flaw was found in the Linux kernel in versions before 5.9-rc6. When changing screen size, an out-of- bounds memory write can occur leading to memory corruption or a denial of service. Due to the nature of the flaw, privilege escalation cannot be fully ruled out. (CVE-2020-14390)

  • A TOCTOU mismatch in the NFS client code in the Linux kernel before 5.8.3 could be used by local attackers to corrupt memory or possibly have unspecified other impact because a size check is in fs/nfs/nfs4proc.c instead of fs/nfs/nfs4xdr.c, aka CID-b4487b935452. (CVE-2020-25212)

  • The rbd block device driver in drivers/block/rbd.c in the Linux kernel through 5.8.9 used incomplete permission checking for access to rbd devices, which could be leveraged by local attackers to map or unmap rbd block devices, aka CID-f44d04e696fe. (CVE-2020-25284)

  • A race condition between hugetlb sysctl handlers in mm/hugetlb.c in the Linux kernel before 5.8.8 could be used by local attackers to corrupt memory, cause a NULL pointer dereference, or possibly have unspecified other impact, aka CID-17743798d812. (CVE-2020-25285)

  • A flaw was found in the Linux kernel’s implementation of biovecs in versions before 5.9-rc7. A zero-length biovec request issued by the block subsystem could cause the kernel to enter an infinite loop, causing a denial of service. This flaw allows a local attacker with basic privileges to issue requests to a block device, resulting in a denial of service. The highest threat from this vulnerability is to system availability. (CVE-2020-25641)

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

##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALASKERNEL-5.4-2022-016.
##

include('compat.inc');

if (description)
{
  script_id(160437);
  script_version("1.5");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/09/05");

  script_cve_id(
    "CVE-2019-19448",
    "CVE-2019-19770",
    "CVE-2020-12888",
    "CVE-2020-14314",
    "CVE-2020-14385",
    "CVE-2020-14390",
    "CVE-2020-25212",
    "CVE-2020-25284",
    "CVE-2020-25285",
    "CVE-2020-25641"
  );

  script_name(english:"Amazon Linux 2 : kernel (ALASKERNEL-5.4-2022-016)");

  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 kernel installed on the remote host is prior to 5.4.68-34.125. It is, therefore, affected by multiple
vulnerabilities as referenced in the ALAS2KERNEL-5.4-2022-016 advisory.

  - In the Linux kernel 5.0.21 and 5.3.11, mounting a crafted btrfs filesystem image, performing some
    operations, and then making a syncfs system call can lead to a use-after-free in try_merge_free_space in
    fs/btrfs/free-space-cache.c because the pointer to a left data structure can be the same as the pointer to
    a right data structure. (CVE-2019-19448)

  - ** DISPUTED ** In the Linux kernel 4.19.83, there is a use-after-free (read) in the debugfs_remove
    function in fs/debugfs/inode.c (which is used to remove a file or directory in debugfs that was previously
    created with a call to another debugfs function such as debugfs_create_file). NOTE: Linux kernel
    developers dispute this issue as not being an issue with debugfs, instead this is an issue with misuse of
    debugfs within blktrace. (CVE-2019-19770)

  - The VFIO PCI driver in the Linux kernel through 5.6.13 mishandles attempts to access disabled memory
    space. (CVE-2020-12888)

  - A memory out-of-bounds read flaw was found in the Linux kernel before 5.9-rc2 with the ext3/ext4 file
    system, in the way it accesses a directory with broken indexing. This flaw allows a local user to crash
    the system if the directory exists. The highest threat from this vulnerability is to system availability.
    (CVE-2020-14314)

  - A flaw was found in the Linux kernel before 5.9-rc4. A failure of the file system metadata validator in
    XFS can cause an inode with a valid, user-creatable extended attribute to be flagged as corrupt. This can
    lead to the filesystem being shutdown, or otherwise rendered inaccessible until it is remounted, leading
    to a denial of service. The highest threat from this vulnerability is to system availability.
    (CVE-2020-14385)

  - A flaw was found in the Linux kernel in versions before 5.9-rc6. When changing screen size, an out-of-
    bounds memory write can occur leading to memory corruption or a denial of service. Due to the nature of
    the flaw, privilege escalation cannot be fully ruled out. (CVE-2020-14390)

  - A TOCTOU mismatch in the NFS client code in the Linux kernel before 5.8.3 could be used by local attackers
    to corrupt memory or possibly have unspecified other impact because a size check is in fs/nfs/nfs4proc.c
    instead of fs/nfs/nfs4xdr.c, aka CID-b4487b935452. (CVE-2020-25212)

  - The rbd block device driver in drivers/block/rbd.c in the Linux kernel through 5.8.9 used incomplete
    permission checking for access to rbd devices, which could be leveraged by local attackers to map or unmap
    rbd block devices, aka CID-f44d04e696fe. (CVE-2020-25284)

  - A race condition between hugetlb sysctl handlers in mm/hugetlb.c in the Linux kernel before 5.8.8 could be
    used by local attackers to corrupt memory, cause a NULL pointer dereference, or possibly have unspecified
    other impact, aka CID-17743798d812. (CVE-2020-25285)

  - A flaw was found in the Linux kernel's implementation of biovecs in versions before 5.9-rc7. A zero-length
    biovec request issued by the block subsystem could cause the kernel to enter an infinite loop, causing a
    denial of service. This flaw allows a local attacker with basic privileges to issue requests to a block
    device, resulting in a denial of service. The highest threat from this vulnerability is to system
    availability. (CVE-2020-25641)

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/AL2/ALASKERNEL-5.4-2022-016.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2019-19448.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2019-19770.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2020-12888.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2020-14314.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2020-14385.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2020-14390.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2020-25212.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2020-25284.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2020-25285.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2020-25641.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update kernel' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2019-19448");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2019-19770");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/12/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2022/01/20");
  script_set_attribute(attribute:"plugin_publication_date", value:"2022/05/02");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-debuginfo-common-aarch64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-debuginfo-common-x86_64");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-headers");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-tools");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-tools-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:kernel-tools-devel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:perf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:perf-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python-perf");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:python-perf-debuginfo");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2022-2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

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

  exit(0);
}

include("rpm.inc");
include("hotfixes.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);

if (get_one_kb_item("Host/kpatch/kernel-cves"))
{
  set_hotfix_type("kpatch");
  var cve_list = make_list("CVE-2019-19448", "CVE-2019-19770", "CVE-2020-12888", "CVE-2020-14314", "CVE-2020-14385", "CVE-2020-14390", "CVE-2020-25212", "CVE-2020-25284", "CVE-2020-25285", "CVE-2020-25641");
  if (hotfix_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, "kpatch hotfix for ALASKERNEL-5.4-2022-016");
  }
  else
  {
    __rpm_report = hotfix_reporting_text();
  }
}
var pkgs = [
    {'reference':'kernel-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-debuginfo-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-debuginfo-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-debuginfo-common-aarch64-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-debuginfo-common-x86_64-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-devel-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-devel-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-headers-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-headers-5.4.68-34.125.amzn2', 'cpu':'i686', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-headers-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-tools-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-tools-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-tools-debuginfo-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-tools-debuginfo-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-tools-devel-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'kernel-tools-devel-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'perf-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'perf-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'perf-debuginfo-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'perf-debuginfo-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'python-perf-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'python-perf-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'python-perf-debuginfo-5.4.68-34.125.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'},
    {'reference':'python-perf-debuginfo-5.4.68-34.125.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE, 'exists_check':'kernel-5.4'}
];

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, "kernel / kernel-debuginfo / kernel-debuginfo-common-x86_64 / etc");
}

References

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