Vulnerabilities > CVE-2017-6920 - Data Processing Errors vulnerability in Drupal

047910
CVSS 7.5 - HIGH
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
PARTIAL
Integrity impact
PARTIAL
Availability impact
PARTIAL
network
low complexity
drupal
CWE-19
nessus

Summary

Drupal core 8 before versions 8.3.4 allows remote attackers to execute arbitrary code due to the PECL YAML parser not handling PHP objects safely during certain operations.

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Overflow Buffers
    Buffer Overflow attacks target improper or missing bounds checking on buffer operations, typically triggered by input injected by an attacker. As a consequence, an attacker is able to write past the boundaries of allocated buffer regions in memory, causing a program crash or potentially redirection of execution as per the attackers' choice.
  • XML Nested Payloads
    Applications often need to transform data in and out of the XML format by using an XML parser. It may be possible for an attacker to inject data that may have an adverse effect on the XML parser when it is being processed. By nesting XML data and causing this data to be continuously self-referential, an attacker can cause the XML parser to consume more resources while processing, causing excessive memory consumption and CPU utilization. An attacker's goal is to leverage parser failure to his or her advantage. In most cases this type of an attack will result in a denial of service due to an application becoming unstable, freezing, or crash. However it may be possible to cause a crash resulting in arbitrary code execution, leading to a jump from the data plane to the control plane [R.230.1].
  • XML Oversized Payloads
    Applications often need to transform data in and out of the XML format by using an XML parser. It may be possible for an attacker to inject data that may have an adverse effect on the XML parser when it is being processed. By supplying oversized payloads in input vectors that will be processed by the XML parser, an attacker can cause the XML parser to consume more resources while processing, causing excessive memory consumption and CPU utilization, and potentially cause execution of arbitrary code. An attacker's goal is to leverage parser failure to his or her advantage. In many cases this type of an attack will result in a denial of service due to an application becoming unstable, freezing, or crash. However it is possible to cause a crash resulting in arbitrary code execution, leading to a jump from the data plane to the control plane [R.231.1].
  • XML Client-Side Attack
    Client applications such as web browsers that process HTML data often need to transform data in and out of the XML format by using an XML parser. It may be possible for an attacker to inject data that may have an adverse effect on the XML parser when it is being processed. These adverse effects may include the parser crashing, consuming too much of a resource, executing too slowly, executing code supplied by an attacker, allowing usage of unintended system functionality, etc. An attacker's goal is to leverage parser failure to his or her advantage. In some cases it may be possible to jump from the data plane to the control plane via bad data being passed to an XML parser. [R.484.1]
  • XML Parser Attack
    Applications often need to transform data in and out of the XML format by using an XML parser. It may be possible for an attacker to inject data that may have an adverse effect on the XML parser when it is being processed. These adverse effects may include the parser crashing, consuming too much of a resource, executing too slowly, executing code supplied by an attacker, allowing usage of unintended system functionality, etc. An attacker's goal is to leverage parser failure to his or her advantage. In some cases it may be possible to jump from the data plane to the control plane via bad data being passed to an XML parser. [R.99.1]

Nessus

  • NASL familyFreeBSD Local Security Checks
    NASL idFREEBSD_PKG_4FC2DF49627911E7BE0F6CF0497DB129.NASL
    descriptionDrupal Security Team Reports : CVE-2017-6920: PECL YAML parser unsafe object handling. CVE-2017-6921: File REST resource does not properly validate CVE-2017-6922: Files uploaded by anonymous users into a private file system can be accessed by other anonymous users.
    last seen2020-06-01
    modified2020-06-02
    plugin id101276
    published2017-07-07
    reporterThis script is Copyright (C) 2017-2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/101276
    titleFreeBSD : drupal -- Drupal Core - Multiple Vulnerabilities (4fc2df49-6279-11e7-be0f-6cf0497db129)
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were  
    # extracted from the FreeBSD VuXML database :
    #
    # Copyright 2003-2018 Jacques Vidrine and contributors
    #
    # Redistribution and use in source (VuXML) and 'compiled' forms (SGML,
    # HTML, PDF, PostScript, RTF and so forth) with or without modification,
    # are permitted provided that the following conditions are met:
    # 1. Redistributions of source code (VuXML) must retain the above
    #    copyright notice, this list of conditions and the following
    #    disclaimer as the first lines of this file unmodified.
    # 2. Redistributions in compiled form (transformed to other DTDs,
    #    published online in any format, converted to PDF, PostScript,
    #    RTF and other formats) must reproduce the above copyright
    #    notice, this list of conditions and the following disclaimer
    #    in the documentation and/or other materials provided with the
    #    distribution.
    # 
    # THIS DOCUMENTATION IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS"
    # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
    # THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
    # PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
    # BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
    # OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
    # OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
    # BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
    # WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
    # OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS DOCUMENTATION,
    # EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(101276);
      script_version("3.5");
      script_cvs_date("Date: 2018/11/10 11:49:46");
    
      script_cve_id("CVE-2017-6920", "CVE-2017-6921", "CVE-2017-6922");
    
      script_name(english:"FreeBSD : drupal -- Drupal Core - Multiple Vulnerabilities (4fc2df49-6279-11e7-be0f-6cf0497db129)");
      script_summary(english:"Checks for updated packages in pkg_info output");
    
      script_set_attribute(
        attribute:"synopsis", 
        value:
    "The remote FreeBSD host is missing one or more security-related
    updates."
      );
      script_set_attribute(
        attribute:"description", 
        value:
    "Drupal Security Team Reports :
    
    CVE-2017-6920: PECL YAML parser unsafe object handling.
    
    CVE-2017-6921: File REST resource does not properly validate
    
    CVE-2017-6922: Files uploaded by anonymous users into a private file
    system can be accessed by other anonymous users."
      );
      # https://vuxml.freebsd.org/freebsd/4fc2df49-6279-11e7-be0f-6cf0497db129.html
      script_set_attribute(
        attribute:"see_also",
        value:"http://www.nessus.org/u?d5d19c09"
      );
      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_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:drupal7");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:drupal8");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:freebsd:freebsd");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2017/06/21");
      script_set_attribute(attribute:"patch_publication_date", value:"2017/07/06");
      script_set_attribute(attribute:"plugin_publication_date", value:"2017/07/07");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2017-2018 and is owned by Tenable, Inc. or an Affiliate thereof.");
      script_family(english:"FreeBSD Local Security Checks");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/FreeBSD/release", "Host/FreeBSD/pkg_info");
    
      exit(0);
    }
    
    
    include("audit.inc");
    include("freebsd_package.inc");
    
    
    if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
    if (!get_kb_item("Host/FreeBSD/release")) audit(AUDIT_OS_NOT, "FreeBSD");
    if (!get_kb_item("Host/FreeBSD/pkg_info")) audit(AUDIT_PACKAGE_LIST_MISSING);
    
    
    flag = 0;
    
    if (pkg_test(save_report:TRUE, pkg:"drupal7<7.56")) flag++;
    if (pkg_test(save_report:TRUE, pkg:"drupal8<8.3.4")) flag++;
    
    if (flag)
    {
      if (report_verbosity > 0) security_hole(port:0, extra:pkg_report_get());
      else security_hole(0);
      exit(0);
    }
    else audit(AUDIT_HOST_NOT, "affected");
    
  • NASL familyCGI abuses
    NASL idDRUPAL_8_3_4.NASL
    descriptionAccording to its self-reported version, the instance of Drupal running on the remote web server is 7.x prior to 7.56 or 8.x prior to 8.3.4. It is, therefore, affected by multiple vulnerabilities : - A flaw exists in the PECL YAML parser due to unsafe handling of PHP objects during certain operations. An unauthenticated, remote attacker can exploit this to execute arbitrary code. (CVE-2017-6920) - A flaw exists in the file REST resource due to improper validation of user-supplied input to multiple fields when manipulating files. An unauthenticated, remote attacker can exploit this to have an unspecified impact on integrity. Note that a site is only affected by this issue if it has the RESTful Web Services (rest) module enabled, the file REST resource is enabled and allows PATCH requests, and the attacker can get or register a user account on the site with permissions to upload files and to modify the file resource. (CVE-2017-6921) - An information disclosure vulnerability exists due to a failure to ensure that private files that have been uploaded by an anonymous user but not permanently attached to content on the site are only visible to the anonymous user who uploaded them instead of all anonymous users. An unauthenticated, remote attacker can exploit this to disclose the files of other anonymous users. (CVE-2017-6922) Note that Nessus has not tested for these issues but has instead relied only on the application
    last seen2020-06-01
    modified2020-06-02
    plugin id101063
    published2017-06-27
    reporterThis script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/101063
    titleDrupal 7.x < 7.56 / 8.x < 8.3.4 Multiple Vulnerabilities (SA-CORE-2017-003)
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(101063);
      script_version("1.9");
      script_cvs_date("Date: 2019/11/13");
    
      script_cve_id("CVE-2017-6920", "CVE-2017-6921", "CVE-2017-6922");
      script_bugtraq_id(99211, 99219, 99222);
    
      script_name(english:"Drupal 7.x < 7.56 / 8.x < 8.3.4 Multiple Vulnerabilities (SA-CORE-2017-003)");
      script_summary(english:"Checks the version of Drupal.");
    
      script_set_attribute(attribute:"synopsis", value:
    "A PHP application running on the remote web server is affected by
    multiple vulnerabilities.");
      script_set_attribute(attribute:"description", value:
    "According to its self-reported version, the instance of Drupal running
    on the remote web server is 7.x prior to 7.56 or 8.x prior to 8.3.4.
    It is, therefore, affected by multiple vulnerabilities :
    
      - A flaw exists in the PECL YAML parser due to unsafe
        handling of PHP objects during certain operations. An
        unauthenticated, remote attacker can exploit this to
        execute arbitrary code. (CVE-2017-6920)
    
      - A flaw exists in the file REST resource due to improper
        validation of user-supplied input to multiple fields
        when manipulating files. An unauthenticated, remote
        attacker can exploit this to have an unspecified impact
        on integrity. Note that a site is only affected by this
        issue if it has the RESTful Web Services (rest) module
        enabled, the file REST resource is enabled and allows
        PATCH requests, and the attacker can get or register a
        user account on the site with permissions to upload
        files and to modify the file resource. (CVE-2017-6921)
    
      - An information disclosure vulnerability exists due to a
        failure to ensure that private files that have been
        uploaded by an anonymous user but not permanently
        attached to content on the site are only visible to the
        anonymous user who uploaded them instead of all
        anonymous users. An unauthenticated, remote attacker can
        exploit this to disclose the files of other anonymous
        users. (CVE-2017-6922)
    
    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://www.drupal.org/SA-CORE-2017-003");
      script_set_attribute(attribute:"see_also", value:"https://www.drupal.org/project/drupal/releases/7.56");
      script_set_attribute(attribute:"see_also", value:"https://www.drupal.org/project/drupal/releases/8.3.4");
      script_set_attribute(attribute:"solution", value:
    "Upgrade to Drupal version 7.56 / 8.3.4 or later.");
      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: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-2017-6920");
    
      script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2017/06/21");
      script_set_attribute(attribute:"patch_publication_date", value:"2017/06/21");
      script_set_attribute(attribute:"plugin_publication_date", value:"2017/06/27");
    
      script_set_attribute(attribute:"potential_vulnerability", value:"true");
      script_set_attribute(attribute:"plugin_type", value:"remote");
      script_set_attribute(attribute:"cpe", value:"cpe:/a:drupal:drupal");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_family(english:"CGI abuses");
    
      script_copyright(english:"This script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");
    
      script_dependencies("drupal_detect.nasl");
      script_require_keys("installed_sw/Drupal", "Settings/ParanoidReport");
      script_require_ports("Services/www", 80, 443);
    
      exit(0);
    }
    
    include("vcf.inc");
    include("http.inc");
    
    if (report_paranoia < 2) audit(AUDIT_PARANOID);
    
    port = get_http_port(default:80, php:TRUE);
    
    app_info = vcf::get_app_info(app:"Drupal", port:port, webapp:true);
    
    vcf::check_granularity(app_info:app_info, sig_segments:2);
    
    constraints = [
      { "min_version" : "7.0", "max_version" : "7.55", "fixed_version" : "7.56" },
      { "min_version" : "8.0", "max_version" : "8.3.3", "fixed_version" : "8.3.4" }
    ];
    
    vcf::check_version_and_report(app_info:app_info, constraints:constraints, severity:SECURITY_HOLE);