Linux Distros Unpatched Vulnerability : CVE-2021-3712

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
##

include('compat.inc');

if (description)
{
  script_id(224076);
  script_version("1.4");
  script_set_attribute(attribute:"plugin_modification_date", value:"2025/12/01");

  script_cve_id("CVE-2021-3712");

  script_name(english:"Linux Distros Unpatched Vulnerability : CVE-2021-3712");

  script_set_attribute(attribute:"synopsis", value:
"The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be
patched.");
  script_set_attribute(attribute:"description", value:
"The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied
patch available.

  - ASN.1 strings are represented internally within OpenSSL as an ASN1_STRING structure which contains a
    buffer holding the string data and a field holding the buffer length. This contrasts with normal C strings
    which are repesented as a buffer for the string data which is terminated with a NUL (0) byte. Although not
    a strict requirement, ASN.1 strings that are parsed using OpenSSL's own d2i functions (and other similar
    parsing functions) as well as any string whose value has been set with the ASN1_STRING_set() function will
    additionally NUL terminate the byte array in the ASN1_STRING structure. However, it is possible for
    applications to directly construct valid ASN1_STRING structures which do not NUL terminate the byte array
    by directly setting the data and length fields in the ASN1_STRING array. This can also happen by using
    the ASN1_STRING_set0() function. Numerous OpenSSL functions that print ASN.1 data have been found to
    assume that the ASN1_STRING byte array will be NUL terminated, even though this is not guaranteed for
    strings that have been directly constructed. Where an application requests an ASN.1 structure to be
    printed, and where that ASN.1 structure contains ASN1_STRINGs that have been directly constructed by the
    application without NUL terminating the data field, then a read buffer overrun can occur. The same thing
    can also occur during name constraints processing of certificates (for example if a certificate has been
    directly constructed by the application instead of loading it via the OpenSSL parsing functions, and the
    certificate contains non NUL terminated ASN1_STRING structures). It can also occur in the
    X509_get1_email(), X509_REQ_get1_email() and X509_get1_ocsp() functions. If a malicious actor can cause an
    application to directly construct an ASN1_STRING and then process it through one of the affected OpenSSL
    functions then this issue could be hit. This might result in a crash (causing a Denial of Service attack).
    It could also result in the disclosure of private memory contents (such as private keys, or sensitive
    plaintext). Fixed in OpenSSL 1.1.1l (Affected 1.1.1-1.1.1k). Fixed in OpenSSL 1.0.2za (Affected
    1.0.2-1.0.2y). (CVE-2021-3712)

Note that Nessus relies on the presence of the package as reported by the vendor.");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/cve-2021-3712");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/CVE-2021-3712");
  script_set_attribute(attribute:"solution", value:
"There is no known solution at this time.");
  script_set_attribute(attribute:"agent", value:"unix");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:N/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:U/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:U/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-3712");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2021/08/24");
  script_set_attribute(attribute:"plugin_publication_date", value:"2025/03/05");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:centos:centos:8");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:redhat:enterprise_linux:8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:edk2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:centos:centos:compat-openssl10");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:redhat:enterprise_linux:compat-openssl10");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Misc.");

  script_copyright(english:"This script is Copyright (C) 2025 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("set_linux_os_id.nasl", "ssh_get_info2.nasl");
  script_require_keys("Host/OS/identifier", "Host/cpu", "Host/local_checks_enabled", "global_settings/vendor_unpatched");
  script_require_ports("Host/OS/CentOS Linux-8", "Host/OS/Red Hat Enterprise Linux-8", "Host/OS/Ubuntu Linux-16.04", "Host/OS/Ubuntu Linux-18.04");

  exit(0);
}

if (!get_kb_item("global_settings/vendor_unpatched")) exit(0, "Unpatched Vulnerabilities Detection not active.");
if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (empty_or_null(get_one_kb_item("Host/CentOS/rpm-list")) && empty_or_null(get_one_kb_item("Host/Debian/dpkg-l")) && empty_or_null(get_one_kb_item("Host/RedHat/rpm-list"))) audit(AUDIT_PACKAGE_LIST_MISSING);

include('linux_unpatched.inc');

var distro_constraints_array = {
  "Ubuntu Linux-16.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "16.04",
        "pkgs": [
          {"reference": "edk2"}
        ]
      }
    ]
  },
  "Ubuntu Linux-18.04": {
    "package_manager": "dpkg-l",
    "constraints": [
      {
        "release": "18.04",
        "pkgs": [
          {"reference": "edk2"}
        ]
      }
    ]
  },
  "CentOS Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "compat-openssl10"}
        ]
      }
    ]
  },
  "Red Hat Enterprise Linux-8": {
    "package_manager": "rpm-list",
    "constraints": [
      {
        "release": "8",
        "pkgs": [
          {"reference": "compat-openssl10"}
        ]
      }
    ]
  }
};

var distro_constraints_values = linux_unpatched::get_distro_constraints(distro_constraints_arr:distro_constraints_array);
if (empty_or_null(distro_constraints_values)) audit(AUDIT_HOST_NOT, 'affected');
var report = linux_unpatched::check_unpatched_constraints(distro_constraints_values:distro_constraints_values);

if (!empty_or_null(report))
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_WARNING,
      extra      : report
  );
  exit(0);
}
else
{
  audit(AUDIT_HOST_NOT, 'affected');
}