Amazon Linux 2 : amazon-ssm-agent (ALAS-2024-2458)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux 2 Security Advisory ALAS-2024-2458.
##

include('compat.inc');

if (description)
{
  script_id(190697);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/04/25");

  script_cve_id(
    "CVE-2023-39325",
    "CVE-2023-39326",
    "CVE-2023-49568",
    "CVE-2023-49569"
  );

  script_name(english:"Amazon Linux 2 : amazon-ssm-agent (ALAS-2024-2458)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Amazon Linux 2 host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The version of amazon-ssm-agent installed on the remote host is prior to 3.2.2222.0-1. It is, therefore, affected by
multiple vulnerabilities as referenced in the ALAS2-2024-2458 advisory.

  - A malicious HTTP/2 client which rapidly creates requests and immediately resets them can cause excessive
    server resource consumption. While the total number of requests is bounded by the
    http2.Server.MaxConcurrentStreams setting, resetting an in-progress request allows the attacker to create
    a new request while the existing one is still executing. With the fix applied, HTTP/2 servers now bound
    the number of simultaneously executing handler goroutines to the stream concurrency limit
    (MaxConcurrentStreams). New requests arriving when at the limit (which can only happen after the client
    has reset an existing, in-flight request) will be queued until a handler exits. If the request queue grows
    too large, the server will terminate the connection. This issue is also fixed in golang.org/x/net/http2
    for users manually configuring HTTP/2. The default stream concurrency limit is 250 streams (requests) per
    HTTP/2 connection. This value may be adjusted using the golang.org/x/net/http2 package; see the
    Server.MaxConcurrentStreams setting and the ConfigureServer function. (CVE-2023-39325)

  - A malicious HTTP sender can use chunk extensions to cause a receiver reading from a request or response
    body to read many more bytes from the network than are in the body. A malicious HTTP client can further
    exploit this to cause a server to automatically read a large amount of data (up to about 1GiB) when a
    handler fails to read the entire body of a request. Chunk extensions are a little-used HTTP feature which
    permit including additional metadata in a request or response body sent using the chunked encoding. The
    net/http chunked encoding reader discards this metadata. A sender can exploit this by inserting a large
    metadata segment with each byte transferred. The chunk reader now produces an error if the ratio of real
    body to encoded bytes grows too small. (CVE-2023-39326)

  - A denial of service (DoS) vulnerability was discovered in go-git versions prior to v5.11. This
    vulnerability allows an attacker to perform denial of service attacks by providing specially crafted
    responses from a Git server which triggers resource exhaustion in go-git clients. Applications using only
    the in-memory filesystem supported by go-git are not affected by this vulnerability. This is a go-git
    implementation issue and does not affect the upstream git cli. (CVE-2023-49568)

  - A path traversal vulnerability was discovered in go-git versions prior to v5.11. This vulnerability allows
    an attacker to create and amend files across the filesystem. In the worse case scenario, remote code
    execution could be achieved. Applications are only affected if they are using the ChrootOS
    https://pkg.go.dev/github.com/go-git/go-billy/v5/osfs#ChrootOS , which is the default when using Plain
    versions of Open and Clone funcs (e.g. PlainClone). Applications using BoundOS
    https://pkg.go.dev/github.com/go-git/go-billy/v5/osfs#BoundOS or in-memory filesystems are not affected by
    this issue. This is a go-git implementation issue and does not affect the upstream git cli.
    (CVE-2023-49569)

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://alas.aws.amazon.com/AL2/ALAS-2024-2458.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/faqs.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2023-39325.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2023-39326.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2023-49568.html");
  script_set_attribute(attribute:"see_also", value:"https://alas.aws.amazon.com/cve/html/CVE-2023-49569.html");
  script_set_attribute(attribute:"solution", value:
"Run 'yum update amazon-ssm-agent' to update your system.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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-2023-49569");

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

  script_set_attribute(attribute:"vuln_publication_date", value:"2024/01/09");
  script_set_attribute(attribute:"patch_publication_date", value:"2024/02/15");
  script_set_attribute(attribute:"plugin_publication_date", value:"2024/02/19");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:amazon-ssm-agent");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:amazon-ssm-agent-debuginfo");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux:2");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 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/AmazonLinux/release", "Host/AmazonLinux/rpm-list");

  exit(0);
}

include("rpm.inc");

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

var alas_release = get_kb_item("Host/AmazonLinux/release");
if (isnull(alas_release) || !strlen(alas_release)) audit(AUDIT_OS_NOT, "Amazon Linux");
var os_ver = pregmatch(pattern: "^AL(A|\d+|-\d+)", string:alas_release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
os_ver = os_ver[1];
if (os_ver != "2")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux 2", "Amazon Linux " + os_ver);
}

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

var pkgs = [
    {'reference':'amazon-ssm-agent-3.2.2222.0-1.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'amazon-ssm-agent-3.2.2222.0-1.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'amazon-ssm-agent-debuginfo-3.2.2222.0-1.amzn2', 'cpu':'aarch64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE},
    {'reference':'amazon-ssm-agent-debuginfo-3.2.2222.0-1.amzn2', 'cpu':'x86_64', 'release':'AL2', 'rpm_spec_vers_cmp':TRUE}
];

var flag = 0;
foreach var package_array ( pkgs ) {
  var reference = NULL;
  var _release = NULL;
  var sp = NULL;
  var _cpu = NULL;
  var el_string = NULL;
  var rpm_spec_vers_cmp = NULL;
  var epoch = NULL;
  var allowmaj = NULL;
  var exists_check = 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['sp'])) sp = package_array['sp'];
  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['epoch'])) epoch = package_array['epoch'];
  if (!empty_or_null(package_array['allowmaj'])) allowmaj = package_array['allowmaj'];
  if (!empty_or_null(package_array['exists_check'])) exists_check = package_array['exists_check'];
  if (reference && _release && (!exists_check || rpm_exists(release:_release, rpm:exists_check))) {
    if (rpm_check(release:_release, sp:sp, cpu:_cpu, reference:reference, epoch:epoch, el_string:el_string, rpm_spec_vers_cmp:rpm_spec_vers_cmp, allowmaj:allowmaj)) flag++;
  }
}

if (flag)
{
  security_report_v4(
      port       : 0,
      severity   : SECURITY_HOLE,
      extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "amazon-ssm-agent / amazon-ssm-agent-debuginfo");
}