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nessusThis script is Copyright (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.EULEROS_SA-2021-1709.NASL
HistoryMar 24, 2021 - 12:00 a.m.

EulerOS 2.0 SP5 : unbound (EulerOS-SA-2021-1709)

2021-03-2400:00:00
This script is Copyright (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
8

6.5 Medium

AI Score

Confidence

High

According to the version of the unbound packages installed, the EulerOS installation on the remote host is affected by the following vulnerability :

  • NLnet Labs Unbound, up to and including version 1.12.0, and NLnet Labs NSD, up to and including version 4.3.3, contain a local vulnerability that would allow for a local symlink attack. When writing the PID file, Unbound and NSD create the file if it is not there, or open an existing file for writing. In case the file was already present, they would follow symlinks if the file happened to be a symlink instead of a regular file. An additional chown of the file would then take place after it was written, making the user Unbound/NSD is supposed to run as the new owner of the file. If an attacker has local access to the user Unbound/NSD runs as, she could create a symlink in place of the PID file pointing to a file that she would like to erase. If then Unbound/NSD is killed and the PID file is not cleared, upon restarting with root privileges, Unbound/NSD will rewrite any file pointed at by the symlink. This is a local vulnerability that could create a Denial of Service of the system Unbound/NSD is running on. It requires an attacker having access to the limited permission user Unbound/NSD runs as and point through the symlink to a critical file on the system.(CVE-2020-28935)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

#%NASL_MIN_LEVEL 70300
#
# (C) Tenable Network Security, Inc.
#

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

if (description)
{
  script_id(148040);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/01/08");

  script_cve_id("CVE-2020-28935");

  script_name(english:"EulerOS 2.0 SP5 : unbound (EulerOS-SA-2021-1709)");

  script_set_attribute(attribute:"synopsis", value:
"The remote EulerOS host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"According to the version of the unbound packages installed, the
EulerOS installation on the remote host is affected by the following
vulnerability :

  - NLnet Labs Unbound, up to and including version 1.12.0,
    and NLnet Labs NSD, up to and including version 4.3.3,
    contain a local vulnerability that would allow for a
    local symlink attack. When writing the PID file,
    Unbound and NSD create the file if it is not there, or
    open an existing file for writing. In case the file was
    already present, they would follow symlinks if the file
    happened to be a symlink instead of a regular file. An
    additional chown of the file would then take place
    after it was written, making the user Unbound/NSD is
    supposed to run as the new owner of the file. If an
    attacker has local access to the user Unbound/NSD runs
    as, she could create a symlink in place of the PID file
    pointing to a file that she would like to erase. If
    then Unbound/NSD is killed and the PID file is not
    cleared, upon restarting with root privileges,
    Unbound/NSD will rewrite any file pointed at by the
    symlink. This is a local vulnerability that could
    create a Denial of Service of the system Unbound/NSD is
    running on. It requires an attacker having access to
    the limited permission user Unbound/NSD runs as and
    point through the symlink to a critical file on the
    system.(CVE-2020-28935)

Note that Tenable Network Security has extracted the preceding
description block directly from the EulerOS security advisory. Tenable
has attempted to automatically clean and format it as much as possible
without introducing additional issues.");
  # https://developer.huaweicloud.com/ict/en/site-euleros/euleros/security-advisories/EulerOS-SA-2021-1709
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?4d0259dc");
  script_set_attribute(attribute:"solution", value:
"Update the affected unbound package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:N/I:N/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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-2020-28935");

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

  script_set_attribute(attribute:"patch_publication_date", value:"2021/03/23");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/03/24");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:unbound");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:unbound-libs");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:huawei:euleros:2.0");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/EulerOS/release", "Host/EulerOS/rpm-list", "Host/EulerOS/sp");
  script_exclude_keys("Host/EulerOS/uvp_version");

  exit(0);
}

include("audit.inc");
include("global_settings.inc");
include("rpm.inc");

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

release = get_kb_item("Host/EulerOS/release");
if (isnull(release) || release !~ "^EulerOS") audit(AUDIT_OS_NOT, "EulerOS");
if (release !~ "^EulerOS release 2\.0(\D|$)") audit(AUDIT_OS_NOT, "EulerOS 2.0");

sp = get_kb_item("Host/EulerOS/sp");
if (isnull(sp) || sp !~ "^(5)$") audit(AUDIT_OS_NOT, "EulerOS 2.0 SP5");

uvp = get_kb_item("Host/EulerOS/uvp_version");
if (!empty_or_null(uvp)) audit(AUDIT_OS_NOT, "EulerOS 2.0 SP5", "EulerOS UVP " + uvp);

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

cpu = get_kb_item("Host/cpu");
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$" && "aarch64" >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "EulerOS", cpu);
if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$") audit(AUDIT_ARCH_NOT, "i686 / x86_64", cpu);

flag = 0;

pkgs = ["unbound-1.6.6-1.h4.eulerosv2r7",
        "unbound-libs-1.6.6-1.h4.eulerosv2r7"];

foreach (pkg in pkgs)
  if (rpm_check(release:"EulerOS-2.0", sp:"5", reference:pkg)) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_NOTE,
    extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "unbound");
}