Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : Git vulnerability (USN-4761-1)

##
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4761-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('compat.inc');

if (description)
{
  script_id(148010);
  script_version("1.5");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/10/16");

  script_cve_id("CVE-2021-21300");
  script_xref(name:"USN", value:"4761-1");

  script_name(english:"Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : Git vulnerability (USN-4761-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 20.10 host has packages installed that are affected by a
vulnerability as referenced in the USN-4761-1 advisory.

  - Git is an open-source distributed revision control system. In affected versions of Git a specially crafted
    repository that contains symbolic links as well as files using a clean/smudge filter such as Git LFS, may
    cause just-checked out script to be executed while cloning onto a case-insensitive file system such as
    NTFS, HFS+ or APFS (i.e. the default file systems on Windows and macOS). Note that clean/smudge filters
    have to be configured for that. Git for Windows configures Git LFS by default, and is therefore
    vulnerable. The problem has been patched in the versions published on Tuesday, March 9th, 2021. As a
    workaound, if symbolic link support is disabled in Git (e.g. via `git config --global core.symlinks
    false`), the described attack won't work. Likewise, if no clean/smudge filters such as Git LFS are
    configured globally (i.e. _before_ cloning), the attack is foiled. As always, it is best to avoid cloning
    repositories from untrusted sources. The earliest impacted version is 2.14.2. The fix versions are:
    2.30.1, 2.29.3, 2.28.1, 2.27.1, 2.26.3, 2.25.5, 2.24.4, 2.23.4, 2.22.5, 2.21.4, 2.20.5, 2.19.6, 2.18.5,
    2.17.62.17.6. (CVE-2021-21300)

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://ubuntu.com/security/notices/USN-4761-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:H/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:F/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:F/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-21300");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"metasploit_name", value:'Git LFS Clone Command Exec');
  script_set_attribute(attribute:"exploit_framework_metasploit", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2021/03/09");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/03/09");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/03/23");

  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:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-all");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-arch");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-cvs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-daemon-run");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-daemon-sysvinit");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-el");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-email");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-gui");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-man");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-mediawiki");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:git-svn");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:gitk");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:gitweb");
  script_end_attributes();

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

  script_copyright(english:"Ubuntu Security Notice (C) 2021-2023 Canonical, Inc. / NASL script (C) 2021-2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

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

  exit(0);
}

include('debian_package.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 (! ('16.04' >< os_release || '18.04' >< os_release || '20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 16.04 / 18.04 / 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 pkgs = [
    {'osver': '16.04', 'pkgname': 'git', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-all', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-arch', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-core', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-cvs', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-daemon-run', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-daemon-sysvinit', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-el', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-email', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-gui', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-man', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-mediawiki', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'git-svn', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'gitk', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '16.04', 'pkgname': 'gitweb', 'pkgver': '1:2.7.4-0ubuntu1.10'},
    {'osver': '18.04', 'pkgname': 'git', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'git-all', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'git-cvs', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'git-daemon-run', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'git-daemon-sysvinit', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'git-el', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'git-email', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'git-gui', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'git-man', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'git-mediawiki', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'git-svn', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'gitk', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '18.04', 'pkgname': 'gitweb', 'pkgver': '1:2.17.1-1ubuntu0.8'},
    {'osver': '20.04', 'pkgname': 'git', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'git-all', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'git-cvs', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'git-daemon-run', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'git-daemon-sysvinit', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'git-el', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'git-email', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'git-gui', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'git-man', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'git-mediawiki', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'git-svn', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'gitk', 'pkgver': '1:2.25.1-1ubuntu3.1'},
    {'osver': '20.04', 'pkgname': 'gitweb', 'pkgver': '1:2.25.1-1ubuntu3.1'}
];

var flag = 0;
foreach package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (osver && pkgname && pkgver) {
    if (ubuntu_check(osver:osver, pkgname:pkgname, pkgver:pkgver)) flag++;
  }
}

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : ubuntu_report_get()
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'git / git-all / git-arch / git-core / git-cvs / git-daemon-run / etc');
}