Vulnerabilities > CVE-2019-3807 - Improper Certificate Validation vulnerability in Powerdns Recursor
Attack vector
NETWORK Attack complexity
LOW Privileges required
NONE Confidentiality impact
HIGH Integrity impact
HIGH Availability impact
HIGH Summary
An issue has been found in PowerDNS Recursor versions 4.1.x before 4.1.9 where records in the answer section of responses received from authoritative servers with the AA flag not set were not properly validated, allowing an attacker to bypass DNSSEC validation.
Vulnerable Configurations
Part | Description | Count |
---|---|---|
Application | 14 |
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_2019-F44F095639.NASL description Fixes CVE-2019-386 and CVE-2019-3807 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 2020-06-01 modified 2020-06-02 plugin id 122138 published 2019-02-13 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/122138 title Fedora 29 : pdns-recursor (2019-f44f095639) code # # (C) Tenable Network Security, Inc. # # The descriptive text and package checks in this plugin were # extracted from Fedora Security Advisory FEDORA-2019-f44f095639. # include("compat.inc"); if (description) { script_id(122138); script_version("1.3"); script_cvs_date("Date: 2020/02/12"); script_cve_id("CVE-2019-3806", "CVE-2019-3807"); script_xref(name:"FEDORA", value:"2019-f44f095639"); script_name(english:"Fedora 29 : pdns-recursor (2019-f44f095639)"); 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: "Fixes CVE-2019-386 and CVE-2019-3807 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-2019-f44f095639" ); script_set_attribute( attribute:"solution", value:"Update the affected pdns-recursor package." ); 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:H/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-2019-3806"); 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:fedoraproject:fedora:pdns-recursor"); script_set_attribute(attribute:"cpe", value:"cpe:/o:fedoraproject:fedora:29"); script_set_attribute(attribute:"vuln_publication_date", value:"2019/01/29"); script_set_attribute(attribute:"patch_publication_date", value:"2019/02/13"); script_set_attribute(attribute:"plugin_publication_date", value:"2019/02/13"); 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:"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:"^29([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "Fedora 29", "Fedora " + os_ver); if (!get_kb_item("Host/RedHat/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING); cpu = get_kb_item("Host/cpu"); if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH); if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$") audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "Fedora", cpu); flag = 0; if (rpm_check(release:"FC29", reference:"pdns-recursor-4.1.9-1.fc29")) 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, "pdns-recursor"); }
NASL family Fedora Local Security Checks NASL id FEDORA_2019-7696BB57CA.NASL description Fixes CVE-2019-386 and CVE-2019-3807 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 2020-06-01 modified 2020-06-02 plugin id 122136 published 2019-02-13 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/122136 title Fedora 28 : pdns-recursor (2019-7696bb57ca) NASL family FreeBSD Local Security Checks NASL id FREEBSD_PKG_40D92CC51E2B11E9BEF66805CA2FA271.NASL description PowerDNS Team reports : CVE-2019-3806: An issue has been found in PowerDNS Recursor where Lua hooks are not properly applied to queries received over TCP in some specific combination of settings, possibly bypassing security policies enforced using Lua. When the recursor is configured to run with more than one thread (threads=X) and to do the distribution of incoming queries to the worker threads itself (pdns-distributes-queries=yes), the Lua script is not properly loaded in the thread handling incoming TCP queries, causing the Lua hooks to not be properly applied. CVE-2019-3807: An issue has been found in PowerDNS Recursor where records in the answer section of responses received from authoritative servers with the AA flag not set were not properly validated, allowing an attacker to bypass DNSSEC validation. last seen 2020-03-18 modified 2019-01-29 plugin id 121427 published 2019-01-29 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/121427 title FreeBSD : powerdns-recursor -- multiple vulnerabilities (40d92cc5-1e2b-11e9-bef6-6805ca2fa271) NASL family SuSE Local Security Checks NASL id OPENSUSE-2019-100.NASL description This update for pdns-recursor fixes the following issues : - CVE-2019-3807: Fixed insufficient validation of DNSSEC signatures (boo#1121889) last seen 2020-03-18 modified 2019-01-30 plugin id 121459 published 2019-01-30 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/121459 title openSUSE Security Update : pdns-recursor (openSUSE-2019-100)