Vulnerabilities > CVE-2017-7821 - Incorrect Permission Assignment for Critical Resource vulnerability in Mozilla Firefox

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
mozilla
CWE-732
critical
nessus
NVD
Published: 2018-06-11
Updated: 2019-10-03

Summary

A vulnerability where WebExtensions can download and attempt to open a file of some non-executable file types. This can be triggered without specific user interaction for the file download and open actions. This could be used to trigger known vulnerabilities in the programs that handle those document types. This vulnerability affects Firefox < 56.

Vulnerable Configurations

Part Description Count
Application
Mozilla
523

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Accessing Functionality Not Properly Constrained by ACLs
    In applications, particularly web applications, access to functionality is mitigated by the authorization framework, whose job it is to map ACLs to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application or can run queries for data that he is otherwise not supposed to.
  • Privilege Abuse
    An adversary is able to exploit features of the target that should be reserved for privileged users or administrators but are exposed to use by lower or non-privileged accounts. Access to sensitive information and functionality must be controlled to ensure that only authorized users are able to access these resources. If access control mechanisms are absent or misconfigured, a user may be able to access resources that are intended only for higher level users. An adversary may be able to exploit this to utilize a less trusted account to gain information and perform activities reserved for more trusted accounts. This attack differs from privilege escalation and other privilege stealing attacks in that the adversary never actually escalates their privileges but instead is able to use a lesser degree of privilege to access resources that should be (but are not) reserved for higher privilege accounts. Likewise, the adversary does not exploit trust or subvert systems - all control functionality is working as configured but the configuration does not adequately protect sensitive resources at an appropriate level.
  • Directory Indexing
    An adversary crafts a request to a target that results in the target listing/indexing the content of a directory as output. One common method of triggering directory contents as output is to construct a request containing a path that terminates in a directory name rather than a file name since many applications are configured to provide a list of the directory's contents when such a request is received. An adversary can use this to explore the directory tree on a target as well as learn the names of files. This can often end up revealing test files, backup files, temporary files, hidden files, configuration files, user accounts, script contents, as well as naming conventions, all of which can be used by an attacker to mount additional attacks.
  • Accessing, Modifying or Executing Executable Files
    An attack of this type exploits a system's configuration that allows an attacker to either directly access an executable file, for example through shell access; or in a possible worst case allows an attacker to upload a file and then execute it. Web servers, ftp servers, and message oriented middleware systems which have many integration points are particularly vulnerable, because both the programmers and the administrators must be in synch regarding the interfaces and the correct privileges for each interface.
  • Exploiting Incorrectly Configured Access Control Security Levels
    An attacker exploits a weakness in the configuration of access controls and is able to bypass the intended protection that these measures guard against and thereby obtain unauthorized access to the system or network. Sensitive functionality should always be protected with access controls. However configuring all but the most trivial access control systems can be very complicated and there are many opportunities for mistakes. If an attacker can learn of incorrectly configured access security settings, they may be able to exploit this in an attack. Most commonly, attackers would take advantage of controls that provided too little protection for sensitive activities in order to perform actions that should be denied to them. In some circumstances, an attacker may be able to take advantage of overly restrictive access control policies, initiating denial of services (if an application locks because it unexpectedly failed to be granted access) or causing other legitimate actions to fail due to security. The latter class of attacks, however, is usually less severe and easier to detect than attacks based on inadequate security restrictions. This attack pattern differs from CAPEC 1, "Accessing Functionality Not Properly Constrained by ACLs" in that the latter describes attacks where sensitive functionality lacks access controls, where, in this pattern, the access control is present, but incorrectly configured.

Nessus

  • NASL familyWindows
    NASL idMOZILLA_FIREFOX_56_0.NASL
    descriptionThe version of Mozilla Firefox installed on the remote Windows host is prior to 56. It is, therefore, affected by multiple vulnerabilities, some of which allow code execution and potentially exploitable crashes.
    last seen2020-06-01
    modified2020-06-02
    plugin id103680
    published2017-10-06
    reporterThis script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/103680
    titleMozilla Firefox < 56 Multiple Vulnerabilities
    code
    #
# (C) Tenable Network Security, Inc.
#

include("compat.inc");

if (description)
{
  script_id(103680);
  script_version("1.4");
  script_cvs_date("Date: 2019/11/12");

  script_cve_id(
    "CVE-2017-7793",
    "CVE-2017-7805",
    "CVE-2017-7810",
    "CVE-2017-7811",
    "CVE-2017-7812",
    "CVE-2017-7813",
    "CVE-2017-7814",
    "CVE-2017-7815",
    "CVE-2017-7816",
    "CVE-2017-7817",
    "CVE-2017-7818",
    "CVE-2017-7819",
    "CVE-2017-7820",
    "CVE-2017-7821",
    "CVE-2017-7822",
    "CVE-2017-7823",
    "CVE-2017-7824"
  );
  script_bugtraq_id(
    101053,
    101054,
    101055,
    101057
  );
  script_xref(name:"MFSA", value:"2017-21");

  script_name(english:"Mozilla Firefox < 56 Multiple Vulnerabilities");
  script_summary(english:"Checks the version of Firefox.");

  script_set_attribute(attribute:"synopsis", value:
"A web browser installed on the remote Windows host is affected by
multiple vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"The version of Mozilla Firefox installed on the remote Windows host is
prior to 56. It is, therefore, affected by multiple vulnerabilities,
some of which allow code execution and potentially exploitable crashes.");
  script_set_attribute(attribute:"see_also", value:"https://www.mozilla.org/en-US/security/advisories/mfsa2017-21/");
  script_set_attribute(attribute:"solution", value:
"Upgrade to Mozilla Firefox version 56 or later.");
  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-2017-7811");

  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:"2017/09/28");
  script_set_attribute(attribute:"patch_publication_date", value:"2017/09/28");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/10/06");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:mozilla:firefox");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Windows");

  script_copyright(english:"This script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("mozilla_org_installed.nasl");
  script_require_keys("Mozilla/Firefox/Version");

  exit(0);
}

include("mozilla_version.inc");

port = get_kb_item("SMB/transport");
if (!port) port = 445;

installs = get_kb_list("SMB/Mozilla/Firefox/*");
if (isnull(installs)) audit(AUDIT_NOT_INST, "Firefox");

mozilla_check_version(installs:installs, product:'firefox', fix:'56', severity:SECURITY_HOLE);
  • NASL familyUbuntu Local Security Checks
    NASL idUBUNTU_USN-3435-1.NASL
    descriptionMultiple security issues were discovered in Firefox. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit these to read uninitialized memory, obtain sensitive information, bypass phishing and malware protection, spoof the origin in modal dialogs, conduct cross-site scripting (XSS) attacks, cause a denial of service via application crash, or execute arbitrary code. (CVE-2017-7793, CVE-2017-7810, CVE-2017-7811, CVE-2017-7812, CVE-2017-7813, CVE-2017-7814, CVE-2017-7815, CVE-2017-7818, CVE-2017-7819, CVE-2017-7820, CVE-2017-7822, CVE-2017-7823, CVE-2017-7824) Martin Thomson discovered that NSS incorrectly generated handshake hashes. A remote attacker could potentially exploit this to cause a denial of service via application crash, or execute arbitrary code. (CVE-2017-7805) Multiple security issues were discovered in WebExtensions. If a user were tricked in to installing a specially crafted extension, an attacker could potentially exploit these to download and open non-executable files without interaction, or obtain elevated privileges. (CVE-2017-7816, CVE-2017-7821). Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. 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 id103646
    published2017-10-03
    reporterUbuntu Security Notice (C) 2017-2019 Canonical, Inc. / NASL script (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/103646
    titleUbuntu 14.04 LTS / 16.04 LTS / 17.04 : firefox vulnerabilities (USN-3435-1)
  • NASL familyUbuntu Local Security Checks
    NASL idUBUNTU_USN-3435-2.NASL
    descriptionUSN-3435-1 fixed vulnerabilities in Firefox. The update caused the Flash plugin to crash in some circumstances. This update fixes the problem. We apologize for the inconvenience. Multiple security issues were discovered in Firefox. If a user were tricked in to opening a specially crafted website, an attacker could potentially exploit these to read uninitialized memory, obtain sensitive information, bypass phishing and malware protection, spoof the origin in modal dialogs, conduct cross-site scripting (XSS) attacks, cause a denial of service via application crash, or execute arbitrary code. (CVE-2017-7793, CVE-2017-7810, CVE-2017-7811, CVE-2017-7812, CVE-2017-7813, CVE-2017-7814, CVE-2017-7815, CVE-2017-7818, CVE-2017-7819, CVE-2017-7820, CVE-2017-7822, CVE-2017-7823, CVE-2017-7824) Martin Thomson discovered that NSS incorrectly generated handshake hashes. A remote attacker could potentially exploit this to cause a denial of service via application crash, or execute arbitrary code. (CVE-2017-7805) Multiple security issues were discovered in WebExtensions. If a user were tricked in to installing a specially crafted extension, an attacker could potentially exploit these to download and open non-executable files without interaction, or obtain elevated privileges. (CVE-2017-7816, CVE-2017-7821). Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. 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 id103667
    published2017-10-05
    reporterUbuntu Security Notice (C) 2017-2019 Canonical, Inc. / NASL script (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/103667
    titleUbuntu 14.04 LTS / 16.04 LTS / 17.04 : firefox regression (USN-3435-2)
  • NASL familyMacOS X Local Security Checks
    NASL idMACOSX_FIREFOX_56_0.NASL
    descriptionThe version of Mozilla Firefox installed on the remote macOS or Mac OS X host is prior to 56. It is, therefore, affected by multiple vulnerabilities, some of which allow code execution and potentially exploitable application crashes.
    last seen2020-06-01
    modified2020-06-02
    plugin id103678
    published2017-10-06
    reporterThis script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/103678
    titleMozilla Firefox < 56 Multiple Vulnerabilities (macOS)
  • NASL familyFreeBSD Local Security Checks
    NASL idFREEBSD_PKG_1098A15BB0F642B7B5C78A8646E8BE07.NASL
    descriptionMozilla Foundation reports : CVE-2017-7793: Use-after-free with Fetch API CVE-2017-7817: Firefox for Android address bar spoofing through fullscreen mode CVE-2017-7818: Use-after-free during ARIA array manipulation CVE-2017-7819: Use-after-free while resizing images in design mode CVE-2017-7824: Buffer overflow when drawing and validating elements with ANGLE CVE-2017-7805: Use-after-free in TLS 1.2 generating handshake hashes CVE-2017-7812: Drag and drop of malicious page content to the tab bar can open locally stored files CVE-2017-7814: Blob and data URLs bypass phishing and malware protection warnings CVE-2017-7813: Integer truncation in the JavaScript parser CVE-2017-7825: OS X fonts render some Tibetan and Arabic unicode characters as spaces CVE-2017-7815: Spoofing attack with modal dialogs on non-e10s installations CVE-2017-7816: WebExtensions can load about: URLs in extension UI CVE-2017-7821: WebExtensions can download and open non-executable files without user interaction CVE-2017-7823: CSP sandbox directive did not create a unique origin CVE-2017-7822: WebCrypto allows AES-GCM with 0-length IV CVE-2017-7820: Xray wrapper bypass with new tab and web console CVE-2017-7811: Memory safety bugs fixed in Firefox 56 CVE-2017-7810: Memory safety bugs fixed in Firefox 56 and Firefox ESR 52.4
    last seen2020-06-01
    modified2020-06-02
    plugin id103556
    published2017-09-29
    reporterThis script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/103556
    titleFreeBSD : mozilla -- multiple vulnerabilities (1098a15b-b0f6-42b7-b5c7-8a8646e8be07)

Seebug

bulletinFamilyexploit
description### CVE-2017-7821 "browser.downloads addon feature may be used for RCE" Steps: 1. Go to 'about:debugging' 2. Unpack attached PoC somewhere 3. Back in 'about:debugging' choose 'Load temp addon' and choose the poc 4. jar file is automatically downloaded and executed. We are able to download and execute jar files automatically.
idSSV:96617
last seen2017-11-19
modified2017-10-09
published2017-10-09
reporterRoot
sourcehttps://www.seebug.org/vuldb/ssvid-96617
titleMozilla Firefox WebExtensions can download and open non-executable files without user interaction(CVE-2017-7821)

References