Amazon Linux AMI : git (ALAS-2021-1490)

##
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux AMI Security Advisory ALAS-2021-1490.
##

include('compat.inc');

if (description)
{
  script_id(148131);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/08/30");

  script_cve_id("CVE-2021-21300");
  script_xref(name:"ALAS", value:"2021-1490");

  script_name(english:"Amazon Linux AMI : git (ALAS-2021-1490)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux AMI host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of git installed on the remote host is prior to 2.18.5-2.73. It is, therefore, affected by a vulnerability
as referenced in the ALAS-2021-1490 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://alas.aws.amazon.com/ALAS-2021-1490.html");
  script_set_attribute(attribute:"see_also", value:"https://access.redhat.com/security/cve/CVE-2021-21300");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update git' to update your system.");
  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:"2021/03/23");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/03/25");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:emacs-git");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:emacs-git-el");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-all");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-bzr");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-core");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-core-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-cvs");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-daemon");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-email");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-hg");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-instaweb");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-p4");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-subtree");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:git-svn");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:gitweb");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:perl-Git");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:perl-Git-SVN");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux");
  script_end_attributes();

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

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

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

  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/AmazonLinux/release");
if (isnull(release) || !strlen(release)) audit(AUDIT_OS_NOT, "Amazon Linux");
os_ver = pregmatch(pattern: "^AL(A|\d)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
os_ver = os_ver[1];
if (os_ver != "A")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux AMI", "Amazon Linux " + os_ver);
}

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

pkgs = [
    {'reference':'emacs-git-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'emacs-git-el-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-2.18.5-2.73.amzn1', 'cpu':'i686', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-2.18.5-2.73.amzn1', 'cpu':'x86_64', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-all-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-bzr-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-core-2.18.5-2.73.amzn1', 'cpu':'i686', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-core-2.18.5-2.73.amzn1', 'cpu':'x86_64', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-core-doc-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-cvs-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-daemon-2.18.5-2.73.amzn1', 'cpu':'i686', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-daemon-2.18.5-2.73.amzn1', 'cpu':'x86_64', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-debuginfo-2.18.5-2.73.amzn1', 'cpu':'i686', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-debuginfo-2.18.5-2.73.amzn1', 'cpu':'x86_64', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-email-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-hg-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-instaweb-2.18.5-2.73.amzn1', 'cpu':'i686', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-instaweb-2.18.5-2.73.amzn1', 'cpu':'x86_64', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-p4-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-subtree-2.18.5-2.73.amzn1', 'cpu':'i686', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-subtree-2.18.5-2.73.amzn1', 'cpu':'x86_64', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-svn-2.18.5-2.73.amzn1', 'cpu':'i686', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'git-svn-2.18.5-2.73.amzn1', 'cpu':'x86_64', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'gitweb-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'perl-Git-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'perl-Git-SVN-2.18.5-2.73.amzn1', 'release':'ALA', 'rpm_spec_vers_cmp':TRUE}
];

flag = 0;
foreach package_array ( pkgs ) {
  reference = NULL;
  release = NULL;
  cpu = NULL;
  el_string = NULL;
  rpm_spec_vers_cmp = NULL;
  allowmaj = 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['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['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (reference && release) {
    if (rpm_check(release:release, cpu:cpu, reference:reference, 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
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "emacs-git / emacs-git-el / git / etc");
}