Vulnerabilities > CVE-2019-5420 - Use of Insufficiently Random Values vulnerability in multiple products

047910
CVSS 9.8 - CRITICAL
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
HIGH
Integrity impact
HIGH
Availability impact
HIGH
network
low complexity
rubyonrails
debian
fedoraproject
CWE-330
critical
nessus
exploit available
metasploit
NVD
Published: 2019-03-27
Updated: 2024-11-21

Summary

A remote code execution vulnerability in development mode Rails <5.2.2.1, <6.0.0.beta3 can allow an attacker to guess the automatically generated development mode secret token. This secret token can be used in combination with other Rails internals to escalate to a remote code execution exploit.

Vulnerable Configurations

Part Description Count
Application
Rubyonrails
376
OS
Debian
1
OS
Fedoraproject
1

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Brute Force
    In this attack, some asset (information, functionality, identity, etc.) is protected by a finite secret value. The attacker attempts to gain access to this asset by using trial-and-error to exhaustively explore all the possible secret values in the hope of finding the secret (or a value that is functionally equivalent) that will unlock the asset. Examples of secrets can include, but are not limited to, passwords, encryption keys, database lookup keys, and initial values to one-way functions. The key factor in this attack is the attackers' ability to explore the possible secret space rapidly. This, in turn, is a function of the size of the secret space and the computational power the attacker is able to bring to bear on the problem. If the attacker has modest resources and the secret space is large, the challenge facing the attacker is intractable. While the defender cannot control the resources available to an attacker, they can control the size of the secret space. Creating a large secret space involves selecting one's secret from as large a field of equally likely alternative secrets as possible and ensuring that an attacker is unable to reduce the size of this field using available clues or cryptanalysis. Doing this is more difficult than it sounds since elimination of patterns (which, in turn, would provide an attacker clues that would help them reduce the space of potential secrets) is difficult to do using deterministic machines, such as computers. Assuming a finite secret space, a brute force attack will eventually succeed. The defender must rely on making sure that the time and resources necessary to do so will exceed the value of the information. For example, a secret space that will likely take hundreds of years to explore is likely safe from raw-brute force attacks.
  • Signature Spoofing by Key Recreation
    An attacker obtains an authoritative or reputable signer's private signature key by exploiting a cryptographic weakness in the signature algorithm or pseudorandom number generation and then uses this key to forge signatures from the original signer to mislead a victim into performing actions that benefit the attacker.
  • Session Credential Falsification through Prediction
    This attack targets predictable session ID in order to gain privileges. The attacker can predict the session ID used during a transaction to perform spoofing and session hijacking.

Exploit-Db

fileexploits/linux/remote/46785.rb
idEDB-ID:46785
last seen2019-05-02
modified2019-05-02
platformlinux
port3000
published2019-05-02
reporterExploit-DB
sourcehttps://www.exploit-db.com/download/46785
titleRuby On Rails - DoubleTap Development Mode secret_key_base Remote Code Execution (Metasploit)
typeremote

Metasploit

descriptionThis module exploits a vulnerability in Ruby on Rails. In development mode, a Rails application would use its name as the secret_key_base, and can be easily extracted by visiting an invalid resource for a path. As a result, this allows a remote user to create and deliver a signed serialized payload, load it by the application, and gain remote code execution.
idMSF:EXPLOIT/MULTI/HTTP/RAILS_DOUBLE_TAP
last seen2020-06-14
modified2019-06-20
published2019-04-25
references
reporterRapid7
sourcehttps://github.com/rapid7/metasploit-framework/blob/master//modules/exploits/multi/http/rails_double_tap.rb
titleRuby On Rails DoubleTap Development Mode secret_key_base Vulnerability

Nessus

NASL familyFedora Local Security Checks
NASL idFEDORA_2019-1CFE24DB5C.NASL
descriptionUpdate Ruby on Rails to 5.2.3. Fixes CVE-2019-5418 CVE-2019-5419 CVE-2019-5420. Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
last seen2020-06-01
modified2020-06-02
plugin id124724
published2019-05-10
reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/124724
titleFedora 30 : 1:rubygem-actionmailer / 1:rubygem-actionpack / etc (2019-1cfe24db5c)
code
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from Fedora Security Advisory FEDORA-2019-1cfe24db5c.
#

include("compat.inc");

if (description)
{
  script_id(124724);
  script_version("1.5");
  script_cvs_date("Date: 2020/01/21");

  script_cve_id("CVE-2019-5418", "CVE-2019-5419", "CVE-2019-5420");
  script_xref(name:"FEDORA", value:"2019-1cfe24db5c");

  script_name(english:"Fedora 30 : 1:rubygem-actionmailer / 1:rubygem-actionpack / etc (2019-1cfe24db5c)");
  script_summary(english:"Checks rpm output for the updated packages.");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Fedora host is missing one or more security updates."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Update Ruby on Rails to 5.2.3. Fixes CVE-2019-5418 CVE-2019-5419
CVE-2019-5420.

Note that Tenable Network Security has extracted the preceding
description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as
possible without introducing additional issues."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bodhi.fedoraproject.org/updates/FEDORA-2019-1cfe24db5c"
  );
  script_set_attribute(attribute:"solution", value:"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/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:L/PR:N/UI:N/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-2019-5420");
  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_set_attribute(attribute:"d2_elliot_name", value:"Rails File Disclosure");
  script_set_attribute(attribute:"exploit_framework_d2_elliot", value:"true");
  script_set_attribute(attribute:"metasploit_name", value:'Ruby On Rails DoubleTap Development Mode secret_key_base Vulnerability');
  script_set_attribute(attribute:"exploit_framework_metasploit", value:"true");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:1:rubygem-actionmailer");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:1:rubygem-actionpack");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:1:rubygem-activerecord");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:1:rubygem-activesupport");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:1:rubygem-rails");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:rubygem-actioncable");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:rubygem-actionview");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:rubygem-activejob");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:rubygem-activemodel");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:rubygem-activestorage");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:rubygem-railties");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:fedoraproject:fedora:30");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/03/27");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/05/10");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/05/10");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Fedora Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/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/RedHat/release");
if (isnull(release) || "Fedora" >!< release) audit(AUDIT_OS_NOT, "Fedora");
os_ver = pregmatch(pattern: "Fedora.*release ([0-9]+)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Fedora");
os_ver = os_ver[1];
if (! preg(pattern:"^30([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "Fedora 30", "Fedora " + os_ver);

if (!get_kb_item("Host/RedHat/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$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Fedora", cpu);


flag = 0;
if (rpm_check(release:"FC30", reference:"rubygem-actionmailer-5.2.3-1.fc30", epoch:"1")) flag++;
if (rpm_check(release:"FC30", reference:"rubygem-actionpack-5.2.3-2.fc30", epoch:"1")) flag++;
if (rpm_check(release:"FC30", reference:"rubygem-activerecord-5.2.3-1.fc30", epoch:"1")) flag++;
if (rpm_check(release:"FC30", reference:"rubygem-activesupport-5.2.3-1.fc30", epoch:"1")) flag++;
if (rpm_check(release:"FC30", reference:"rubygem-rails-5.2.3-1.fc30", epoch:"1")) flag++;
if (rpm_check(release:"FC30", reference:"rubygem-actioncable-5.2.3-1.fc30")) flag++;
if (rpm_check(release:"FC30", reference:"rubygem-actionview-5.2.3-2.fc30")) flag++;
if (rpm_check(release:"FC30", reference:"rubygem-activejob-5.2.3-1.fc30")) flag++;
if (rpm_check(release:"FC30", reference:"rubygem-activemodel-5.2.3-2.fc30")) flag++;
if (rpm_check(release:"FC30", reference:"rubygem-activestorage-5.2.3-1.fc30")) flag++;
if (rpm_check(release:"FC30", reference:"rubygem-railties-5.2.3-1.fc30")) flag++;


if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    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, "1:rubygem-actionmailer / 1:rubygem-actionpack / etc");
}

Packetstorm

data sourcehttps://packetstormsecurity.com/files/download/152704/rails_double_tap.rb.txt
idPACKETSTORM:152704
last seen2019-05-02
published2019-05-01
reportersinn3r
sourcehttps://packetstormsecurity.com/files/152704/Ruby-On-Rails-DoubleTap-Development-Mode-secret_key_base-Remote-Code-Execution.html
titleRuby On Rails DoubleTap Development Mode secret_key_base Remote Code Execution

References