Vulnerabilities > CVE-2017-7468 - Improper Certificate Validation vulnerability in Haxx Libcurl
Attack vector
NETWORK Attack complexity
LOW Privileges required
NONE Confidentiality impact
NONE Integrity impact
HIGH Availability impact
NONE Summary
In curl and libcurl 7.52.0 to and including 7.53.1, libcurl would attempt to resume a TLS session even if the client certificate had changed. That is unacceptable since a server by specification is allowed to skip the client certificate check on resume, and may instead use the old identity which was established by the previous certificate (or no certificate). libcurl supports by default the use of TLS session id/ticket to resume previous TLS sessions to speed up subsequent TLS handshakes. They are used when for any reason an existing TLS connection couldn't be kept alive to make the next handshake faster. This flaw is a regression and identical to CVE-2016-5419 reported on August 3rd 2016, but affecting a different version range.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| Application | 4 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Creating a Rogue Certificate Authority Certificate An attacker exploits a weakness in the MD5 hash algorithm (weak collision resistance) to generate a certificate signing request (CSR) that contains collision blocks in the "to be signed" part. The attacker specially crafts two different, but valid X.509 certificates that when hashed with the MD5 algorithm would yield the same value. The attacker then sends the CSR for one of the certificates to the Certification Authority which uses the MD5 hashing algorithm. That request is completely valid and the Certificate Authority issues an X.509 certificate to the attacker which is signed with its private key. An attacker then takes that signed blob and inserts it into another X.509 certificate that the attacker generated. Due to the MD5 collision, both certificates, though different, hash to the same value and so the signed blob works just as well in the second certificate. The net effect is that the attackers' second X.509 certificate, which the Certification Authority has never seen, is now signed and validated by that Certification Authority. To make the attack more interesting, the second certificate could be not just a regular certificate, but rather itself a signing certificate. Thus the attacker is able to start their own Certification Authority that is anchored in its root of trust in the legitimate Certification Authority that has signed the attackers' first X.509 certificate. If the original Certificate Authority was accepted by default by browsers, so will now the Certificate Authority set up by the attacker and of course any certificates that it signs. So the attacker is now able to generate any SSL certificates to impersonate any web server, and the user's browser will not issue any warning to the victim. This can be used to compromise HTTPS communications and other types of systems where PKI and X.509 certificates may be used (e.g., VPN, IPSec) .
Nessus
NASL family Fedora Local Security Checks NASL id FEDORA_2017-3EEC07CB06.NASL description - fix switching off SSL session id when client cert is used (CVE-2017-7468) 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 2017-07-17 plugin id 101616 published 2017-07-17 reporter This script is Copyright (C) 2017-2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/101616 title Fedora 26 : curl (2017-3eec07cb06) 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-2017-3eec07cb06. # include("compat.inc"); if (description) { script_id(101616); script_version("3.4"); script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/04"); script_cve_id("CVE-2017-7468"); script_xref(name:"FEDORA", value:"2017-3eec07cb06"); script_name(english:"Fedora 26 : curl (2017-3eec07cb06)"); 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: " - fix switching off SSL session id when client cert is used (CVE-2017-7468) 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-2017-3eec07cb06" ); script_set_attribute(attribute:"solution", value:"Update the affected curl package."); script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N"); script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:curl"); script_set_attribute(attribute:"cpe", value:"cpe:/o:fedoraproject:fedora:26"); script_set_attribute(attribute:"vuln_publication_date", value:"2018/07/16"); script_set_attribute(attribute:"patch_publication_date", value:"2017/04/21"); script_set_attribute(attribute:"plugin_publication_date", value:"2017/07/17"); script_set_attribute(attribute:"generated_plugin", value:"current"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_copyright(english:"This script is Copyright (C) 2017-2020 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:"^26([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "Fedora 26", "Fedora " + os_ver); if (!get_kb_item("Host/RedHat/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING); cpu = get_kb_item("Host/cpu"); if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH); if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Fedora", cpu); flag = 0; if (rpm_check(release:"FC26", reference:"curl-7.53.1-6.fc26")) 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, "curl"); }NASL family Ubuntu Local Security Checks NASL id UBUNTU_USN-3262-1.NASL description It was discovered that curl incorrectly handled client certificates when resuming a TLS session. A remote attacker could use this to hijack a previously authenticated connection. 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 99582 published 2017-04-21 reporter Ubuntu Security Notice (C) 2017-2019 Canonical, Inc. / NASL script (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/99582 title Ubuntu 17.04 : curl vulnerability (USN-3262-1) code # # (C) Tenable Network Security, Inc. # # The descriptive text and package checks in this plugin were # extracted from Ubuntu Security Notice USN-3262-1. 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(99582); script_version("3.7"); script_cvs_date("Date: 2019/09/18 12:31:46"); script_cve_id("CVE-2017-7468"); script_xref(name:"USN", value:"3262-1"); script_name(english:"Ubuntu 17.04 : curl vulnerability (USN-3262-1)"); script_summary(english:"Checks dpkg output for updated packages."); script_set_attribute( attribute:"synopsis", value: "The remote Ubuntu host is missing one or more security-related patches." ); script_set_attribute( attribute:"description", value: "It was discovered that curl incorrectly handled client certificates when resuming a TLS session. A remote attacker could use this to hijack a previously authenticated connection. 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/3262-1/" ); 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:P/A:N"); 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:N/I:H/A:N"); script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C"); script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available"); script_set_attribute(attribute:"exploit_available", value:"false"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:curl"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libcurl3"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libcurl3-gnutls"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libcurl3-nss"); script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:17.04"); script_set_attribute(attribute:"vuln_publication_date", value:"2018/07/16"); script_set_attribute(attribute:"patch_publication_date", value:"2017/04/20"); script_set_attribute(attribute:"plugin_publication_date", value:"2017/04/21"); script_set_attribute(attribute:"generated_plugin", value:"current"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_copyright(english:"Ubuntu Security Notice (C) 2017-2019 Canonical, Inc. / NASL script (C) 2017-2019 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:"^(17\.04)$", string:release)) audit(AUDIT_OS_NOT, "Ubuntu 17.04", "Ubuntu " + release); if ( ! get_kb_item("Host/Debian/dpkg-l") ) audit(AUDIT_PACKAGE_LIST_MISSING); cpu = get_kb_item("Host/cpu"); if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH); if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Ubuntu", cpu); flag = 0; if (ubuntu_check(osver:"17.04", pkgname:"curl", pkgver:"7.52.1-4ubuntu1.1")) flag++; if (ubuntu_check(osver:"17.04", pkgname:"libcurl3", pkgver:"7.52.1-4ubuntu1.1")) flag++; if (ubuntu_check(osver:"17.04", pkgname:"libcurl3-gnutls", pkgver:"7.52.1-4ubuntu1.1")) flag++; if (ubuntu_check(osver:"17.04", pkgname:"libcurl3-nss", pkgver:"7.52.1-4ubuntu1.1")) 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, "curl / libcurl3 / libcurl3-gnutls / libcurl3-nss"); }NASL family Gentoo Local Security Checks NASL id GENTOO_GLSA-201709-14.NASL description The remote host is affected by the vulnerability described in GLSA-201709-14 (cURL: Multiple vulnerabilities) Multiple vulnerabilities have been discovered in cURL. Please review the CVE identifiers referenced below for details. Impact : Remote attackers could cause a Denial of Service condition, obtain sensitive information, or bypass intended restrictions for TLS sessions. Workaround : There is no known workaround at this time. last seen 2020-06-01 modified 2020-06-02 plugin id 103282 published 2017-09-18 reporter This script is Copyright (C) 2017-2018 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/103282 title GLSA-201709-14 : cURL: Multiple vulnerabilities NASL family MacOS X Local Security Checks NASL id MACOSX_SECUPD2017-003.NASL description The remote host is running Mac OS X 10.10.5, Mac OS X 10.11.6, or macOS 10.12.5 and is missing a security update. It is therefore, affected by multiple vulnerabilities : - An overflow condition exists in the curl component in the dprintf_formatf() function that is triggered when handling floating point conversion. An unauthenticated, remote attacker can exploit this to cause a denial of service condition or the execution of arbitrary code. (CVE-2016-9586) - A flaw exits in the curl component in the randit() function within file lib/rand.c due to improper initialization of the 32-bit random value, which is used, for example, to generate Digest and NTLM authentication nonces, resulting in weaker cryptographic operations than expected. (CVE-2016-9594) - A flaw exists in the curl component in the allocate_conn() function in lib/url.c when using the OCSP stapling feature for checking a X.509 certificate revocation status. The issue is triggered as the request option for OCSP stapling is not properly passed to the TLS library, resulting in no error being returned even when no proof of the validity of the certificate could be provided. A man-in-the-middle attacker can exploit this to provide a revoked certificate. (CVE-2017-2629) - A remote code execution vulnerability exists in the CoreAudio component due to improper validation of user-supplied input when handling movie files. An unauthenticated, remote attacker can exploit this, by convincing a user to play a specially crafted movie file, to cause a denial of service condition or the execution of arbitrary code. (CVE-2017-7008) - A memory corruption issue exists in the IOUSBFamily component due to improper validation of user-supplied input. A local attacker can exploit this, via a specially crafted application, to cause a denial of service condition or the execution of arbitrary code. (CVE-2017-7009) - Multiple out-of-bounds read errors exist in the libxml2 component due to improper handling of specially crafted XML documents. An unauthenticated, remote attacker can exploit these to disclose user information. (CVE-2017-7010, CVE-2017-7013) - Multiple memory corruption issues exist in the Intel Graphics Driver component due to improper validation of input. A local attacker can exploit these issues to execute arbitrary code with elevated privileges. (CVE-2017-7014, CVE-2017-7017, CVE-2017-7035, CVE-2017-7044) - A remote code execution vulnerability exists in the Audio component due to improper validation of user-supplied input when handling audio files. An unauthenticated, remote attacker can exploit this, by convincing a user to play a specially crafted audio file, to execute arbitrary code. (CVE-2017-7015) - Multiple remote code execution vulnerabilities exist in the afclip component due to improper validation of user-supplied input when handling audio files. An unauthenticated, remote attacker can exploit these vulnerabilities, by convincing a user to play a specially crafted audio file, to execute arbitrary code. (CVE-2017-7016, CVE-2017-7033) - A memory corruption issue exists in the AppleGraphicsPowerManagement component due to improper validation of input. A local attacker can exploit this to cause a denial of service condition or the execution of arbitrary code with system privileges. (CVE-2017-7021) - Multiple memory corruption issues exist in the kernel due to improper validation of input. A local attacker can exploit these issues to cause a denial of service condition or the execution of arbitrary code with system privileges. (CVE-2017-7022, CVE-2017-7024, CVE-2017-7026) - Multiple memory corruption issues exist in the kernel due to improper validation of input. A local attacker can exploit these issues to cause a denial of service condition or the execution of arbitrary code with kernel privileges. (CVE-2017-7023, CVE-2017-7025, CVE-2017-7027, CVE-2017-7069) - Multiple unspecified flaws exist in the kernel due to a failure to properly sanitize input. A local attacker can exploit these issues, via a specially crafted application, to disclose restricted memory contents. (CVE-2017-7028, CVE-2017-7029, CVE-2017-7067) - A flaw exists in the Foundation component due to improper validation of input. A unauthenticated, remote attacker can exploit this, by convincing a user to open specially crafted file, to execute arbitrary code. (CVE-2017-7031) - A memory corruption issue exists in the last seen 2020-06-01 modified 2020-06-02 plugin id 101957 published 2017-07-25 reporter This script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/101957 title macOS and Mac OS X Multiple Vulnerabilities (Security Update 2017-003) NASL family Firewalls NASL id PFSENSE_SA-17_04.NASL description According to its self-reported version number, the remote pfSense install is affected by multiple vulnerabilities as stated in the referenced vendor advisories. last seen 2020-06-01 modified 2020-06-02 plugin id 106504 published 2018-01-31 reporter This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/106504 title pfSense < 2.3.4 Multiple Vulnerabilities (SA-17_04) NASL family FreeBSD Local Security Checks NASL id FREEBSD_PKG_3E2E9B4425CE11E7A175939B30E0836D.NASL description cURL security advisory : libcurl would attempt to resume a TLS session even if the client certificate had changed. That is unacceptable since a server by specification is allowed to skip the client certificate check on resume, and may instead use the old identity which was established by the previous certificate (or no certificate). libcurl supports by default the use of TLS session id/ticket to resume previous TLS sessions to speed up subsequent TLS handshakes. They are used when for any reason an existing TLS connection couldn last seen 2020-06-01 modified 2020-06-02 plugin id 99552 published 2017-04-21 reporter This script is Copyright (C) 2017-2018 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/99552 title FreeBSD : cURL -- TLS session resumption client cert bypass (again) (3e2e9b44-25ce-11e7-a175-939b30e0836d)