Ubuntu 20.04 LTS : Linux kernel (OEM) vulnerabilities (USN-5096-1)

#%NASL_MIN_LEVEL 70300
##
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-5096-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('deprecated_nasl_level.inc');
include('compat.inc');

if (description)
{
  script_id(153789);
  script_version("1.5");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/01/09");

  script_cve_id(
    "CVE-2021-3612",
    "CVE-2021-3679",
    "CVE-2021-3732",
    "CVE-2021-34556",
    "CVE-2021-35477",
    "CVE-2021-37159",
    "CVE-2021-38160",
    "CVE-2021-38166",
    "CVE-2021-38199",
    "CVE-2021-38201",
    "CVE-2021-38202",
    "CVE-2021-38203",
    "CVE-2021-38204",
    "CVE-2021-38205",
    "CVE-2021-40490",
    "CVE-2021-41073"
  );
  script_xref(name:"USN", value:"5096-1");

  script_name(english:"Ubuntu 20.04 LTS : Linux kernel (OEM) vulnerabilities (USN-5096-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 20.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in
the USN-5096-1 advisory.

  - In the Linux kernel through 5.13.7, an unprivileged BPF program can obtain sensitive information from
    kernel memory via a Speculative Store Bypass side-channel attack because the protection mechanism neglects
    the possibility of uninitialized memory locations on the BPF stack. (CVE-2021-34556)

  - In the Linux kernel through 5.13.7, an unprivileged BPF program can obtain sensitive information from
    kernel memory via a Speculative Store Bypass side-channel attack because a certain preempting store
    operation does not necessarily occur before a store operation that has an attacker-controlled value.
    (CVE-2021-35477)

  - An out-of-bounds memory write flaw was found in the Linux kernel's joystick devices subsystem in versions
    before 5.9-rc1, in the way the user calls ioctl JSIOCSBTNMAP. This flaw allows a local user to crash the
    system or possibly escalate their privileges on the system. The highest threat from this vulnerability is
    to confidentiality, integrity, as well as system availability. (CVE-2021-3612)

  - A lack of CPU resource in the Linux kernel tracing module functionality in versions prior to 5.14-rc3 was
    found in the way user uses trace ring buffer in a specific way. Only privileged local users (with
    CAP_SYS_ADMIN capability) could use this flaw to starve the resources causing denial of service.
    (CVE-2021-3679)

  - hso_free_net_device in drivers/net/usb/hso.c in the Linux kernel through 5.13.4 calls unregister_netdev
    without checking for the NETREG_REGISTERED state, leading to a use-after-free and a double free.
    (CVE-2021-37159)

  - A flaw was found in the Linux kernel's OverlayFS subsystem in the way the user mounts the TmpFS filesystem
    with OverlayFS. This flaw allows a local user to gain access to hidden files that should not be
    accessible. (CVE-2021-3732)

  - In drivers/char/virtio_console.c in the Linux kernel before 5.13.4, data corruption or loss can be
    triggered by an untrusted device that supplies a buf->len value exceeding the buffer size. NOTE: the
    vendor indicates that the cited data corruption is not a vulnerability in any existing use case; the
    length validation was added solely for robustness in the face of anomalous host OS behavior
    (CVE-2021-38160)

  - In kernel/bpf/hashtab.c in the Linux kernel through 5.13.8, there is an integer overflow and out-of-bounds
    write when many elements are placed in a single bucket. NOTE: exploitation might be impractical without
    the CAP_SYS_ADMIN capability. (CVE-2021-38166)

  - fs/nfs/nfs4client.c in the Linux kernel before 5.13.4 has incorrect connection-setup ordering, which
    allows operators of remote NFSv4 servers to cause a denial of service (hanging of mounts) by arranging for
    those servers to be unreachable during trunking detection. (CVE-2021-38199)

  - net/sunrpc/xdr.c in the Linux kernel before 5.13.4 allows remote attackers to cause a denial of service
    (xdr_set_page_base slab-out-of-bounds access) by performing many NFS 4.2 READ_PLUS operations.
    (CVE-2021-38201)

  - fs/nfsd/trace.h in the Linux kernel before 5.13.4 might allow remote attackers to cause a denial of
    service (out-of-bounds read in strlen) by sending NFS traffic when the trace event framework is being used
    for nfsd. (CVE-2021-38202)

  - btrfs in the Linux kernel before 5.13.4 allows attackers to cause a denial of service (deadlock) via
    processes that trigger allocation of new system chunks during times when there is a shortage of free space
    in the system space_info. (CVE-2021-38203)

  - drivers/usb/host/max3421-hcd.c in the Linux kernel before 5.13.6 allows physically proximate attackers to
    cause a denial of service (use-after-free and panic) by removing a MAX-3421 USB device in certain
    situations. (CVE-2021-38204)

  - drivers/net/ethernet/xilinx/xilinx_emaclite.c in the Linux kernel before 5.13.3 makes it easier for
    attackers to defeat an ASLR protection mechanism because it prints a kernel pointer (i.e., the real IOMEM
    pointer). (CVE-2021-38205)

  - A race condition was discovered in ext4_write_inline_data_end in fs/ext4/inline.c in the ext4 subsystem in
    the Linux kernel through 5.13.13. (CVE-2021-40490)

  - loop_rw_iter in fs/io_uring.c in the Linux kernel 5.10 through 5.14.6 allows local users to gain
    privileges by using IORING_OP_PROVIDE_BUFFERS to trigger a free of a kernel buffer, as demonstrated by
    using /proc/<pid>/maps for exploitation. (CVE-2021-41073)

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://ubuntu.com/security/notices/USN-5096-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected kernel package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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-2021-41073");

  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:"2021/07/09");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/09/29");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/09/30");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:linux-image-5.13.0-1014-oem");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  script_copyright(english:"Ubuntu Security Notice (C) 2021-2024 Canonical, Inc. / NASL script (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl", "linux_alt_patch_detect.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');
include('ksplice.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 20.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);

var kernel_mappings = {
  '20.04': {
    '5.13.0': {
      'oem': '5.13.0-1014'
    }
  }
};

var host_kernel_release = get_kb_item('Host/uptrack-uname-r');
if (empty_or_null(host_kernel_release)) host_kernel_release = get_kb_item_or_exit('Host/uname-r');
var host_kernel_base_version = get_kb_item_or_exit('Host/Debian/kernel-base-version');
var host_kernel_type = get_kb_item_or_exit('Host/Debian/kernel-type');
if(empty_or_null(kernel_mappings[os_release][host_kernel_base_version][host_kernel_type])) audit(AUDIT_INST_VER_NOT_VULN, 'kernel ' + host_kernel_release);

var extra = '';
var kernel_fixed_version = kernel_mappings[os_release][host_kernel_base_version][host_kernel_type] + "-" + host_kernel_type;
if (deb_ver_cmp(ver1:host_kernel_release, ver2:kernel_fixed_version) < 0)
{
  extra = extra + 'Running Kernel level of ' + host_kernel_release + ' does not meet the minimum fixed level of ' + kernel_fixed_version + ' for this advisory.\n\n';
}
  else
{
  audit(AUDIT_PATCH_INSTALLED, 'Kernel package for USN-5096-1');
}

if (get_one_kb_item('Host/ksplice/kernel-cves'))
{
  var cve_list = make_list('CVE-2021-3612', 'CVE-2021-3679', 'CVE-2021-3732', 'CVE-2021-34556', 'CVE-2021-35477', 'CVE-2021-37159', 'CVE-2021-38160', 'CVE-2021-38166', 'CVE-2021-38199', 'CVE-2021-38201', 'CVE-2021-38202', 'CVE-2021-38203', 'CVE-2021-38204', 'CVE-2021-38205', 'CVE-2021-40490', 'CVE-2021-41073');
  if (ksplice_cves_check(cve_list))
  {
    audit(AUDIT_PATCH_INSTALLED, 'KSplice hotfix for USN-5096-1');
  }
  else
  {
    extra = extra + ksplice_reporting_text();
  }
}
if (extra) {
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}