Vulnerabilities > CVE-2019-17007 - Improper Certificate Validation vulnerability in multiple products
Attack vector
NETWORK Attack complexity
LOW Privileges required
NONE Confidentiality impact
NONE Integrity impact
NONE Availability impact
HIGH Summary
In Network Security Services before 3.44, a malformed Netscape Certificate Sequence can cause NSS to crash, resulting in a denial of service.
Vulnerable Configurations
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 Debian Local Security Checks NASL id DEBIAN_DSA-4579.NASL description Two vulnerabilities were discovered in NSS, a set of cryptographic libraries, which may result in denial of service and potentially the execution of arbitrary code. last seen 2020-06-01 modified 2020-06-02 plugin id 131784 published 2019-12-09 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/131784 title Debian DSA-4579-1 : nss - security update code # # (C) Tenable Network Security, Inc. # # The descriptive text and package checks in this plugin were # extracted from Debian Security Advisory DSA-4579. The text # itself is copyright (C) Software in the Public Interest, Inc. # include("compat.inc"); if (description) { script_id(131784); script_version("1.3"); script_cvs_date("Date: 2020/01/15"); script_cve_id("CVE-2019-11745", "CVE-2019-17007"); script_xref(name:"DSA", value:"4579"); script_name(english:"Debian DSA-4579-1 : nss - security update"); script_summary(english:"Checks dpkg output for the updated package"); script_set_attribute( attribute:"synopsis", value:"The remote Debian host is missing a security-related update." ); script_set_attribute( attribute:"description", value: "Two vulnerabilities were discovered in NSS, a set of cryptographic libraries, which may result in denial of service and potentially the execution of arbitrary code." ); script_set_attribute( attribute:"see_also", value:"https://security-tracker.debian.org/tracker/source-package/nss" ); script_set_attribute( attribute:"see_also", value:"https://packages.debian.org/source/buster/nss" ); script_set_attribute( attribute:"see_also", value:"https://www.debian.org/security/2019/dsa-4579" ); script_set_attribute( attribute:"solution", value: "Upgrade the nss packages. For the stable distribution (buster), these problems have been fixed in version 2:3.42.1-1+deb10u2." ); script_set_cvss_base_vector("CVSS2#AV:N/AC:M/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:R/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-2019-11745"); script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:nss"); script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:10.0"); script_set_attribute(attribute:"vuln_publication_date", value:"2020/01/08"); script_set_attribute(attribute:"patch_publication_date", value:"2019/12/06"); script_set_attribute(attribute:"plugin_publication_date", value:"2019/12/09"); script_set_attribute(attribute:"generated_plugin", value:"current"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_copyright(english:"This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof."); script_family(english:"Debian Local Security Checks"); script_dependencies("ssh_get_info.nasl"); script_require_keys("Host/local_checks_enabled", "Host/Debian/release", "Host/Debian/dpkg-l"); exit(0); } include("audit.inc"); include("debian_package.inc"); if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED); if (!get_kb_item("Host/Debian/release")) audit(AUDIT_OS_NOT, "Debian"); if (!get_kb_item("Host/Debian/dpkg-l")) audit(AUDIT_PACKAGE_LIST_MISSING); flag = 0; if (deb_check(release:"10.0", prefix:"libnss3", reference:"2:3.42.1-1+deb10u2")) flag++; if (deb_check(release:"10.0", prefix:"libnss3-dev", reference:"2:3.42.1-1+deb10u2")) flag++; if (deb_check(release:"10.0", prefix:"libnss3-tools", reference:"2:3.42.1-1+deb10u2")) flag++; if (flag) { if (report_verbosity > 0) security_warning(port:0, extra:deb_report_get()); else security_warning(0); exit(0); } else audit(AUDIT_HOST_NOT, "affected");
NASL family Debian Local Security Checks NASL id DEBIAN_DLA-2015.NASL description Handling of Netscape Certificate Sequences in CERT_DecodeCertPackage() may haved crash with a NULL deref leading to a denial of service. For Debian 8 last seen 2020-06-01 modified 2020-06-02 plugin id 131433 published 2019-12-03 reporter This script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/131433 title Debian DLA-2015-1 : nss security update NASL family Ubuntu Local Security Checks NASL id UBUNTU_USN-4215-1.NASL description It was discovered that NSS incorrectly handled certain certificates. An attacker could possibly use this issue to cause a denial of service. 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 131923 published 2019-12-10 reporter Ubuntu Security Notice (C) 2019 Canonical, Inc. / NASL script (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/131923 title Ubuntu 16.04 LTS / 18.04 LTS / 19.04 : nss vulnerability (USN-4215-1)
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1533216
- https://bugzilla.mozilla.org/show_bug.cgi?id=1533216
- https://cert-portal.siemens.com/productcert/pdf/ssa-379803.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-379803.pdf
- https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/NSS_3.44_release_notes
- https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/NSS_3.44_release_notes
- https://us-cert.cisa.gov/ics/advisories/icsa-21-040-04
- https://us-cert.cisa.gov/ics/advisories/icsa-21-040-04