Vulnerabilities > CVE-2017-6921 - Improper Input Validation vulnerability in Drupal

047910
CVSS 5.9 - MEDIUM
Attack vector
NETWORK
Attack complexity
HIGH
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
HIGH
Availability impact
NONE
network
high complexity
drupal
CWE-20
nessus

Summary

In Drupal 8 prior to 8.3.4; The file REST resource does not properly validate some fields when manipulating files. A site is only affected by this if the site has the RESTful Web Services (rest) module enabled, the file REST resource is enabled and allows PATCH requests, and an attacker can get or register a user account on the site with permissions to upload files and to modify the file resource.

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Buffer Overflow via Environment Variables
    This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
  • Server Side Include (SSI) Injection
    An attacker can use Server Side Include (SSI) Injection to send code to a web application that then gets executed by the web server. Doing so enables the attacker to achieve similar results to Cross Site Scripting, viz., arbitrary code execution and information disclosure, albeit on a more limited scale, since the SSI directives are nowhere near as powerful as a full-fledged scripting language. Nonetheless, the attacker can conveniently gain access to sensitive files, such as password files, and execute shell commands.
  • Cross Zone Scripting
    An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security. In a zone-based model, pages belong to one of a set of zones corresponding to the level of privilege assigned to that page. Pages in an untrusted zone would have a lesser level of access to the system and/or be restricted in the types of executable content it was allowed to invoke. In a cross-zone scripting attack, a page that should be assigned to a less privileged zone is granted the privileges of a more trusted zone. This can be accomplished by exploiting bugs in the browser, exploiting incorrect configuration in the zone controls, through a cross-site scripting attack that causes the attackers' content to be treated as coming from a more trusted page, or by leveraging some piece of system functionality that is accessible from both the trusted and less trusted zone. This attack differs from "Restful Privilege Escalation" in that the latter correlates to the inadequate securing of RESTful access methods (such as HTTP DELETE) on the server, while cross-zone scripting attacks the concept of security zones as implemented by a browser.
  • Cross Site Scripting through Log Files
    An attacker may leverage a system weakness where logs are susceptible to log injection to insert scripts into the system's logs. If these logs are later viewed by an administrator through a thin administrative interface and the log data is not properly HTML encoded before being written to the page, the attackers' scripts stored in the log will be executed in the administrative interface with potentially serious consequences. This attack pattern is really a combination of two other attack patterns: log injection and stored cross site scripting.
  • Command Line Execution through SQL Injection
    An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.

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);