Vulnerabilities > CVE-2018-6198 - Link Following vulnerability in multiple products
Attack vector
LOCAL Attack complexity
HIGH Privileges required
LOW Confidentiality impact
NONE Integrity impact
HIGH Availability impact
NONE Summary
w3m through 0.5.3 does not properly handle temporary files when the ~/.w3m directory is unwritable, which allows a local attacker to craft a symlink attack to overwrite arbitrary files.
Vulnerable Configurations
Part | Description | Count |
---|---|---|
Application | Tats
| 19 |
OS | 4 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Symlink Attack An attacker positions a symbolic link in such a manner that the targeted user or application accesses the link's endpoint, assuming that it is accessing a file with the link's name. The endpoint file may be either output or input. If the file is output, the result is that the endpoint is modified, instead of a file at the intended location. Modifications to the endpoint file may include appending, overwriting, corrupting, changing permissions, or other modifications. In some variants of this attack the attacker may be able to control the change to a file while in other cases they cannot. The former is especially damaging since the attacker may be able to grant themselves increased privileges or insert false information, but the latter can also be damaging as it can expose sensitive information or corrupt or destroy vital system or application files. Alternatively, the endpoint file may serve as input to the targeted application. This can be used to feed malformed input into the target or to cause the target to process different information, possibly allowing the attacker to control the actions of the target or to cause the target to expose information to the attacker. Moreover, the actions taken on the endpoint file are undertaken with the permissions of the targeted user or application, which may exceed the permissions that the attacker would normally have.
- 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.
- Leverage Executable Code in Non-Executable Files An attack of this type exploits a system's trust in configuration and resource files, when the executable loads the resource (such as an image file or configuration file) the attacker has modified the file to either execute malicious code directly or manipulate the target process (e.g. application server) to execute based on the malicious configuration parameters. Since systems are increasingly interrelated mashing up resources from local and remote sources the possibility of this attack occurring is high. The attack can be directed at a client system, such as causing buffer overrun through loading seemingly benign image files, as in Microsoft Security Bulletin MS04-028 where specially crafted JPEG files could cause a buffer overrun once loaded into the browser. Another example targets clients reading pdf files. In this case the attacker simply appends javascript to the end of a legitimate url for a pdf (http://www.gnucitizen.org/blog/danger-danger-danger/) http://path/to/pdf/file.pdf#whatever_name_you_want=javascript:your_code_here The client assumes that they are reading a pdf, but the attacker has modified the resource and loaded executable javascript into the client's browser process. The attack can also target server processes. The attacker edits the resource or configuration file, for example a web.xml file used to configure security permissions for a J2EE app server, adding role name "public" grants all users with the public role the ability to use the administration functionality. The server trusts its configuration file to be correct, but when they are manipulated, the attacker gains full control.
- Manipulating Input to File System Calls An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.
Nessus
NASL family Fedora Local Security Checks NASL id FEDORA_2018-0AD6E73AC0.NASL description Rebase to latest upstream gitrev 20180125 and Security fix for CVE-2018-6196, CVE-2018-6197, CVE-2018-6198 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 seen 2020-06-05 modified 2018-02-09 plugin id 106698 published 2018-02-09 reporter This script is Copyright (C) 2018-2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/106698 title Fedora 27 : w3m (2018-0ad6e73ac0) code #%NASL_MIN_LEVEL 80502 # # (C) Tenable Network Security, Inc. # # The descriptive text and package checks in this plugin were # extracted from Fedora Security Advisory FEDORA-2018-0ad6e73ac0. # include("compat.inc"); if (description) { script_id(106698); script_version("3.4"); script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/04"); script_cve_id("CVE-2018-6196", "CVE-2018-6197", "CVE-2018-6198"); script_xref(name:"FEDORA", value:"2018-0ad6e73ac0"); script_name(english:"Fedora 27 : w3m (2018-0ad6e73ac0)"); script_summary(english:"Checks rpm output for the updated package."); script_set_attribute( attribute:"synopsis", value:"The remote Fedora host is missing a security update." ); script_set_attribute( attribute:"description", value: "Rebase to latest upstream gitrev 20180125 and Security fix for CVE-2018-6196, CVE-2018-6197, CVE-2018-6198 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-2018-0ad6e73ac0" ); script_set_attribute(attribute:"solution", value:"Update the affected w3m package."); script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P"); script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:w3m"); script_set_attribute(attribute:"cpe", value:"cpe:/o:fedoraproject:fedora:27"); script_set_attribute(attribute:"vuln_publication_date", value:"2018/01/25"); script_set_attribute(attribute:"patch_publication_date", value:"2018/02/08"); script_set_attribute(attribute:"plugin_publication_date", value:"2018/02/09"); script_set_attribute(attribute:"generated_plugin", value:"current"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_copyright(english:"This script is Copyright (C) 2018-2020 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:"^27([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "Fedora 27", "Fedora " + os_ver); if (!get_kb_item("Host/RedHat/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING); cpu = get_kb_item("Host/cpu"); if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH); if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Fedora", cpu); flag = 0; if (rpm_check(release:"FC27", reference:"w3m-0.5.3-36.git20180125.fc27")) flag++; if (flag) { security_report_v4( port : 0, severity : SECURITY_WARNING, 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, "w3m"); }
NASL family FreeBSD Local Security Checks NASL id FREEBSD_PKG_E72D5BF507A011E882480021CCB9E74D.NASL description Tatsuya Kinoshita reports : CVE-2018-6196 * table.c: Prevent negative indent value in feed_table_block_tag(). CVE-2018-6197 * form.c: Prevent invalid columnPos() call in formUpdateBuffer(). CVE-2018-6198 * config.h.dist, config.h.in, configure, configure.ac, main.c, rc.c: Make temporary directory safely when ~/.w3m is unwritable. last seen 2020-06-01 modified 2020-06-02 plugin id 106600 published 2018-02-05 reporter This script is Copyright (C) 2018 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/106600 title FreeBSD : w3m - multiple vulnerabilities (e72d5bf5-07a0-11e8-8248-0021ccb9e74d) 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(106600); script_version("3.4"); script_cvs_date("Date: 2018/11/10 11:49:47"); script_cve_id("CVE-2018-6196", "CVE-2018-6197", "CVE-2018-6198"); script_name(english:"FreeBSD : w3m - multiple vulnerabilities (e72d5bf5-07a0-11e8-8248-0021ccb9e74d)"); 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: "Tatsuya Kinoshita reports : CVE-2018-6196 * table.c: Prevent negative indent value in feed_table_block_tag(). CVE-2018-6197 * form.c: Prevent invalid columnPos() call in formUpdateBuffer(). CVE-2018-6198 * config.h.dist, config.h.in, configure, configure.ac, main.c, rc.c: Make temporary directory safely when ~/.w3m is unwritable." ); # https://github.com/tats/w3m/commit/e773a0e089276f82c546447c0fd1e6c0f9156628 script_set_attribute( attribute:"see_also", value:"http://www.nessus.org/u?a1a0dafb" ); # https://vuxml.freebsd.org/freebsd/e72d5bf5-07a0-11e8-8248-0021ccb9e74d.html script_set_attribute( attribute:"see_also", value:"http://www.nessus.org/u?44d3ba43" ); script_set_attribute(attribute:"solution", value:"Update the affected packages."); script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P"); script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:ja-w3m"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:ja-w3m-img"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:w3m"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:freebsd:freebsd:w3m-img"); script_set_attribute(attribute:"cpe", value:"cpe:/o:freebsd:freebsd"); script_set_attribute(attribute:"vuln_publication_date", value:"2018/01/25"); script_set_attribute(attribute:"patch_publication_date", value:"2018/02/01"); script_set_attribute(attribute:"plugin_publication_date", value:"2018/02/05"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_copyright(english:"This script is Copyright (C) 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:"w3m<0.5.3.20180125")) flag++; if (pkg_test(save_report:TRUE, pkg:"w3m-img<0.5.3.20180125")) flag++; if (pkg_test(save_report:TRUE, pkg:"ja-w3m<0.5.3.20180125")) flag++; if (pkg_test(save_report:TRUE, pkg:"ja-w3m-img<0.5.3.20180125")) flag++; if (flag) { if (report_verbosity > 0) security_warning(port:0, extra:pkg_report_get()); else security_warning(0); exit(0); } else audit(AUDIT_HOST_NOT, "affected");
NASL family Ubuntu Local Security Checks NASL id UBUNTU_USN-3555-1.NASL description It was discovered that w3m incorrectly handled certain inputs. An attacker could possibly use this to cause a denial of service. (CVE-2018-6196, CVE-2018-6197) It was discovered that w3m incorrectly handled temporary files. An attacker could possibly use this to overwrite arbitrary files. (CVE-2018-6198). 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 seen 2020-06-01 modified 2020-06-02 plugin id 106581 published 2018-02-02 reporter Ubuntu Security Notice (C) 2018-2019 Canonical, Inc. / NASL script (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/106581 title Ubuntu 14.04 LTS / 16.04 LTS / 17.10 : w3m vulnerabilities (USN-3555-1) code # # (C) Tenable Network Security, Inc. # # The descriptive text and package checks in this plugin were # extracted from Ubuntu Security Notice USN-3555-1. The text # itself is copyright (C) Canonical, Inc. See # <http://www.ubuntu.com/usn/>. Ubuntu(R) is a registered # trademark of Canonical, Inc. # include("compat.inc"); if (description) { script_id(106581); script_version("3.5"); script_cvs_date("Date: 2019/09/18 12:31:48"); script_cve_id("CVE-2018-6196", "CVE-2018-6197", "CVE-2018-6198"); script_xref(name:"USN", value:"3555-1"); script_name(english:"Ubuntu 14.04 LTS / 16.04 LTS / 17.10 : w3m vulnerabilities (USN-3555-1)"); script_summary(english:"Checks dpkg output for updated package."); script_set_attribute( attribute:"synopsis", value:"The remote Ubuntu host is missing a security-related patch." ); script_set_attribute( attribute:"description", value: "It was discovered that w3m incorrectly handled certain inputs. An attacker could possibly use this to cause a denial of service. (CVE-2018-6196, CVE-2018-6197) It was discovered that w3m incorrectly handled temporary files. An attacker could possibly use this to overwrite arbitrary files. (CVE-2018-6198). 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." ); script_set_attribute( attribute:"see_also", value:"https://usn.ubuntu.com/3555-1/" ); script_set_attribute(attribute:"solution", value:"Update the affected w3m package."); script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P"); script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:w3m"); script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04"); script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04"); script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:17.10"); script_set_attribute(attribute:"vuln_publication_date", value:"2018/01/25"); script_set_attribute(attribute:"patch_publication_date", value:"2018/02/01"); script_set_attribute(attribute:"plugin_publication_date", value:"2018/02/02"); script_set_attribute(attribute:"generated_plugin", value:"current"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_copyright(english:"Ubuntu Security Notice (C) 2018-2019 Canonical, Inc. / NASL script (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof."); script_family(english:"Ubuntu Local Security Checks"); script_dependencies("ssh_get_info.nasl"); script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l"); exit(0); } include("audit.inc"); include("ubuntu.inc"); include("misc_func.inc"); if ( ! get_kb_item("Host/local_checks_enabled") ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED); release = get_kb_item("Host/Ubuntu/release"); if ( isnull(release) ) audit(AUDIT_OS_NOT, "Ubuntu"); release = chomp(release); if (! preg(pattern:"^(14\.04|16\.04|17\.10)$", string:release)) audit(AUDIT_OS_NOT, "Ubuntu 14.04 / 16.04 / 17.10", "Ubuntu " + release); if ( ! get_kb_item("Host/Debian/dpkg-l") ) audit(AUDIT_PACKAGE_LIST_MISSING); cpu = get_kb_item("Host/cpu"); if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH); if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Ubuntu", cpu); flag = 0; if (ubuntu_check(osver:"14.04", pkgname:"w3m", pkgver:"0.5.3-15ubuntu0.2")) flag++; if (ubuntu_check(osver:"16.04", pkgname:"w3m", pkgver:"0.5.3-26ubuntu0.2")) flag++; if (ubuntu_check(osver:"17.10", pkgname:"w3m", pkgver:"0.5.3-34ubuntu0.1")) flag++; if (flag) { security_report_v4( port : 0, severity : SECURITY_WARNING, extra : ubuntu_report_get() ); exit(0); } else { tested = ubuntu_pkg_tests_get(); if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested); else audit(AUDIT_PACKAGE_NOT_INSTALLED, "w3m"); }
NASL family SuSE Local Security Checks NASL id SUSE_SU-2019-0776-1.NASL description This update for w3m fixes several issues. These security issues were fixed : CVE-2018-6196: Prevent infinite recursion in HTMLlineproc0 caused by the feed_table_block_tag function which did not prevent a negative indent value (bsc#1077559) CVE-2018-6197: Prevent NULL pointer dereference in formUpdateBuffer (bsc#1077568) CVE-2018-6198: w3m did not properly handle temporary files when the ~/.w3m directory is unwritable, which allowed a local attacker to craft a symlink attack to overwrite arbitrary files (bsc#1077572) Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues. last seen 2020-06-01 modified 2020-06-02 plugin id 123450 published 2019-03-28 reporter This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/123450 title SUSE SLED12 / SLES12 Security Update : w3m (SUSE-SU-2019:0776-1) NASL family SuSE Local Security Checks NASL id OPENSUSE-2019-1142.NASL description This update for w3m fixes the following issues : Security issues fixed : - CVE-2018-6196: Prevent infinite recursion in HTMLlineproc0 caused by the feed_table_block_tag function which did not prevent a negative indent value (bsc#1077559) - CVE-2018-6197: Prevent NULL pointer dereference in formUpdateBuffer (bsc#1077568) - CVE-2018-6198: w3m did not properly handle temporary files when the ~/.w3m directory is unwritable, which allowed a local attacker to craft a symlink attack to overwrite arbitrary files (bsc#1077572) This update was imported from the SUSE:SLE-12:Update update project. last seen 2020-06-01 modified 2020-06-02 plugin id 123772 published 2019-04-05 reporter This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/123772 title openSUSE Security Update : w3m (openSUSE-2019-1142)
References
- https://salsa.debian.org/debian/w3m/commit/18dcbadf2771cdb0c18509b14e4e73505b242753
- https://github.com/tats/w3m/commit/18dcbadf2771cdb0c18509b14e4e73505b242753
- https://bugs.debian.org/888097
- http://www.securityfocus.com/bid/102855
- https://usn.ubuntu.com/3555-2/
- https://usn.ubuntu.com/3555-1/
- http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00028.html