Vulnerabilities > CVE-2020-10995 - Resource Exhaustion vulnerability in multiple products

047910
CVSS 7.5 - HIGH
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
NONE
Availability impact
HIGH

Summary

PowerDNS Recursor from 4.1.0 up to and including 4.3.0 does not sufficiently defend against amplification attacks. An issue in the DNS protocol has been found that allow malicious parties to use recursive DNS services to attack third party authoritative name servers. The attack uses a crafted reply by an authoritative name server to amplify the resulting traffic between the recursive and other authoritative name servers. Both types of service can suffer degraded performance as an effect. This is triggered by random subdomains in the NSDNAME in NS records. PowerDNS Recursor 4.1.16, 4.2.2 and 4.3.1 contain a mitigation to limit the impact of this DNS protocol issue.

Common Attack Pattern Enumeration and Classification (CAPEC)

  • XML Ping of the Death
    An attacker initiates a resource depletion attack where a large number of small XML messages are delivered at a sufficiently rapid rate to cause a denial of service or crash of the target. Transactions such as repetitive SOAP transactions can deplete resources faster than a simple flooding attack because of the additional resources used by the SOAP protocol and the resources necessary to process SOAP messages. The transactions used are immaterial as long as they cause resource utilization on the target. In other words, this is a normal flooding attack augmented by using messages that will require extra processing on the target.
  • XML Entity Expansion
    An attacker submits an XML document to a target application where the XML document uses nested entity expansion to produce an excessively large output XML. XML allows the definition of macro-like structures that can be used to simplify the creation of complex structures. However, this capability can be abused to create excessive demands on a processor's CPU and memory. A small number of nested expansions can result in an exponential growth in demands on memory.
  • Inducing Account Lockout
    An attacker leverages the security functionality of the system aimed at thwarting potential attacks to launch a denial of service attack against a legitimate system user. Many systems, for instance, implement a password throttling mechanism that locks an account after a certain number of incorrect log in attempts. An attacker can leverage this throttling mechanism to lock a legitimate user out of their own account. The weakness that is being leveraged by an attacker is the very security feature that has been put in place to counteract attacks.
  • Violating Implicit Assumptions Regarding XML Content (aka XML Denial of Service (XDoS))
    XML Denial of Service (XDoS) can be applied to any technology that utilizes XML data. This is, of course, most distributed systems technology including Java, .Net, databases, and so on. XDoS is most closely associated with web services, SOAP, and Rest, because remote service requesters can post malicious XML payloads to the service provider designed to exhaust the service provider's memory, CPU, and/or disk space. The main weakness in XDoS is that the service provider generally must inspect, parse, and validate the XML messages to determine routing, workflow, security considerations, and so on. It is exactly these inspection, parsing, and validation routines that XDoS targets. There are three primary attack vectors that XDoS can navigate Target CPU through recursion: attacker creates a recursive payload and sends to service provider Target memory through jumbo payloads: service provider uses DOM to parse XML. DOM creates in memory representation of XML document, but when document is very large (for example, north of 1 Gb) service provider host may exhaust memory trying to build memory objects. XML Ping of death: attack service provider with numerous small files that clog the system. All of the above attacks exploit the loosely coupled nature of web services, where the service provider has little to no control over the service requester and any messages the service requester sends.

Nessus

  • NASL familySuSE Local Security Checks
    NASL idOPENSUSE-2020-698.NASL
    descriptionThis update for pdns-recursor fixes the following issues : - update to 4.1.16 - fixes an issue where records in the answer section of a NXDOMAIN response lacking an SOA were not properly validated (CVE-2020-12244, boo#1171553) - fixes an issue where invalid hostname on the server can result in disclosure of invalid memory (CVE-2020-10030, boo#1171553) - fixes an issue in the DNS protocol has been found that allows malicious parties to use recursive DNS services to attack third party authoritative name servers (CVE-2020-10995, boo#1171553) For details see https://doc.powerdns.com/recursor/changelog/4.1.html#change-4.1.16
    last seen2020-05-31
    modified2020-05-26
    plugin id136885
    published2020-05-26
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/136885
    titleopenSUSE Security Update : pdns-recursor (openSUSE-2020-698)
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were
    # extracted from openSUSE Security Update openSUSE-2020-698.
    #
    # The text description of this plugin is (C) SUSE LLC.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(136885);
      script_version("1.2");
      script_set_attribute(attribute:"plugin_modification_date", value:"2020/05/28");
    
      script_cve_id("CVE-2020-10030", "CVE-2020-10995", "CVE-2020-12244");
    
      script_name(english:"openSUSE Security Update : pdns-recursor (openSUSE-2020-698)");
      script_summary(english:"Check for the openSUSE-2020-698 patch");
    
      script_set_attribute(
        attribute:"synopsis",
        value:"The remote openSUSE host is missing a security update."
      );
      script_set_attribute(
        attribute:"description",
        value:
    "This update for pdns-recursor fixes the following issues :
    
      - update to 4.1.16
    
      - fixes an issue where records in the answer section of a
        NXDOMAIN response lacking an SOA were not properly
        validated (CVE-2020-12244, boo#1171553)
    
      - fixes an issue where invalid hostname on the server can
        result in disclosure of invalid memory (CVE-2020-10030,
        boo#1171553)
    
      - fixes an issue in the DNS protocol has been found that
        allows malicious parties to use recursive DNS services
        to attack third party authoritative name servers
        (CVE-2020-10995, boo#1171553)
    
    For details see
    https://doc.powerdns.com/recursor/changelog/4.1.html#change-4.1.16"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://bugzilla.opensuse.org/show_bug.cgi?id=1171553"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://doc.powerdns.com/recursor/changelog/4.1.html#change-4.1.16"
      );
      script_set_attribute(
        attribute:"solution",
        value:"Update the affected pdns-recursor packages."
      );
      script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/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:L/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:"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:novell:opensuse:pdns-recursor");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:pdns-recursor-debuginfo");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:pdns-recursor-debugsource");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:novell:opensuse:15.1");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2020/05/19");
      script_set_attribute(attribute:"patch_publication_date", value:"2020/05/23");
      script_set_attribute(attribute:"plugin_publication_date", value:"2020/05/26");
      script_set_attribute(attribute:"generated_plugin", value:"current");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
      script_family(english:"SuSE Local Security Checks");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/SuSE/release", "Host/SuSE/rpm-list", "Host/cpu");
    
      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/SuSE/release");
    if (isnull(release) || release =~ "^(SLED|SLES)") audit(AUDIT_OS_NOT, "openSUSE");
    if (release !~ "^(SUSE15\.1)$") audit(AUDIT_OS_RELEASE_NOT, "openSUSE", "15.1", release);
    if (!get_kb_item("Host/SuSE/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);
    
    ourarch = get_kb_item("Host/cpu");
    if (!ourarch) audit(AUDIT_UNKNOWN_ARCH);
    if (ourarch !~ "^(x86_64)$") audit(AUDIT_ARCH_NOT, "x86_64", ourarch);
    
    flag = 0;
    
    if ( rpm_check(release:"SUSE15.1", reference:"pdns-recursor-4.1.12-lp151.3.3.1") ) flag++;
    if ( rpm_check(release:"SUSE15.1", reference:"pdns-recursor-debuginfo-4.1.12-lp151.3.3.1") ) flag++;
    if ( rpm_check(release:"SUSE15.1", reference:"pdns-recursor-debugsource-4.1.12-lp151.3.3.1") ) flag++;
    
    if (flag)
    {
      if (report_verbosity > 0) security_warning(port:0, extra:rpm_report_get());
      else security_warning(0);
      exit(0);
    }
    else
    {
      tested = pkg_tests_get();
      if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
      else audit(AUDIT_PACKAGE_NOT_INSTALLED, "pdns-recursor / pdns-recursor-debuginfo / pdns-recursor-debugsource");
    }
    
  • NASL familyFreeBSD Local Security Checks
    NASL idFREEBSD_PKG_F9C5A4109B4E11EAAC3F6805CA2FA271.NASL
    descriptionPowerDNS Team reports : CVE-2020-10995: An issue in the DNS protocol has been found that allow malicious parties to use recursive DNS services to attack third party authoritative name servers. The attack uses a crafted reply by an authoritative name server to amplify the resulting traffic between the recursive and other authoritative name servers. Both types of service can suffer degraded performance as an effect. CVE-2020-12244: An issue has been found in PowerDNS Recursor 4.1.0 through 4.3.0 where records in the answer section of a NXDOMAIN response lacking an SOA were not properly validated in SyncRes::processAnswer. This would allow an attacker in position of man-in-the-middle to send a NXDOMAIN answer for a name that does exist, bypassing DNSSEC validation. CVE-2020-10030: An issue has been found in PowerDNS Authoritative Server allowing an attacker with enough privileges to change the system
    last seen2020-06-06
    modified2020-05-28
    plugin id136942
    published2020-05-28
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/136942
    titleFreeBSD : powerdns-recursor -- multiple vulnerabilities (f9c5a410-9b4e-11ea-ac3f-6805ca2fa271)
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were  
    # extracted from the FreeBSD VuXML database :
    #
    # Copyright 2003-2020 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(136942);
      script_version("1.3");
      script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/05");
    
      script_cve_id("CVE-2020-10030", "CVE-2020-10995", "CVE-2020-12244");
    
      script_name(english:"FreeBSD : powerdns-recursor -- multiple vulnerabilities (f9c5a410-9b4e-11ea-ac3f-6805ca2fa271)");
      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:
    "PowerDNS Team reports :
    
    CVE-2020-10995: An issue in the DNS protocol has been found that allow
    malicious parties to use recursive DNS services to attack third party
    authoritative name servers. The attack uses a crafted reply by an
    authoritative name server to amplify the resulting traffic between the
    recursive and other authoritative name servers. Both types of service
    can suffer degraded performance as an effect.
    
    CVE-2020-12244: An issue has been found in PowerDNS Recursor 4.1.0
    through 4.3.0 where records in the answer section of a NXDOMAIN
    response lacking an SOA were not properly validated in
    SyncRes::processAnswer. This would allow an attacker in position of
    man-in-the-middle to send a NXDOMAIN answer for a name that does
    exist, bypassing DNSSEC validation.
    
    CVE-2020-10030: An issue has been found in PowerDNS Authoritative
    Server allowing an attacker with enough privileges to change the
    system's hostname to cause disclosure of uninitialized memory content
    via a stack-based out-of-bounds read. It only occurs on systems where
    gethostname() does not null-terminate the returned string if the
    hostname is larger than the supplied buffer. Linux systems are not
    affected because the buffer is always large enough. OpenBSD systems
    are not affected because the returned hostname is always
    null-terminated. Under some conditions this issue can lead to the
    writing of one null-byte out-of-bounds on the stack, causing a denial
    of service or possibly arbitrary code execution."
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://doc.powerdns.com/recursor/security-advisories/index.html"
      );
      # https://vuxml.freebsd.org/freebsd/f9c5a410-9b4e-11ea-ac3f-6805ca2fa271.html
      script_set_attribute(
        attribute:"see_also",
        value:"http://www.nessus.org/u?72d79f2a"
      );
      script_set_attribute(attribute:"solution", value:"Update the affected packages.");
      script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:S/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:L/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:"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:freebsd:freebsd:powerdns-recursor");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:freebsd:freebsd");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2020/05/19");
      script_set_attribute(attribute:"patch_publication_date", value:"2020/05/26");
      script_set_attribute(attribute:"plugin_publication_date", value:"2020/05/28");
      script_set_attribute(attribute:"generated_plugin", value:"current");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2020 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:"powerdns-recursor>=4.3.0<4.3.1")) flag++;
    if (pkg_test(save_report:TRUE, pkg:"powerdns-recursor>=4.2.0<4.2.2")) flag++;
    if (pkg_test(save_report:TRUE, pkg:"powerdns-recursor>=4.1.0<4.1.16")) 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 familyDebian Local Security Checks
    NASL idDEBIAN_DSA-4691.NASL
    descriptionTwo vulnerabilities have been discovered in PDNS Recursor, a resolving name server; a traffic amplification attack against third-party authoritative name servers (NXNSAttack) and insufficient validation of NXDOMAIN responses lacking an SOA. The version of pdns-recursor in the oldstable distribution (stretch) is no longer supported. If these security issues affect your setup, you should upgrade to the stable distribution (buster).
    last seen2020-05-31
    modified2020-05-22
    plugin id136778
    published2020-05-22
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/136778
    titleDebian DSA-4691-1 : pdns-recursor - security update
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were  
    # extracted from Debian Security Advisory DSA-4691. The text 
    # itself is copyright (C) Software in the Public Interest, Inc.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(136778);
      script_version("1.2");
      script_set_attribute(attribute:"plugin_modification_date", value:"2020/05/26");
    
      script_cve_id("CVE-2020-10995", "CVE-2020-12244");
      script_xref(name:"DSA", value:"4691");
    
      script_name(english:"Debian DSA-4691-1 : pdns-recursor - 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 have been discovered in PDNS Recursor, a resolving
    name server; a traffic amplification attack against third-party
    authoritative name servers (NXNSAttack) and insufficient validation of
    NXDOMAIN responses lacking an SOA.
    
    The version of pdns-recursor in the oldstable distribution (stretch)
    is no longer supported. If these security issues affect your setup,
    you should upgrade to the stable distribution (buster)."
      );
      # https://security-tracker.debian.org/tracker/source-package/pdns-recursor
      script_set_attribute(
        attribute:"see_also",
        value:"http://www.nessus.org/u?51aad11d"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://packages.debian.org/source/buster/pdns-recursor"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://www.debian.org/security/2020/dsa-4691"
      );
      script_set_attribute(
        attribute:"solution",
        value:
    "Upgrade the pdns-recursor packages.
    
    For the stable distribution (buster), these problems have been fixed
    in version 4.1.11-1+deb10u1."
      );
      script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:N/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:H/I:N/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:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:pdns-recursor");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:10.0");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2020/05/19");
      script_set_attribute(attribute:"patch_publication_date", value:"2020/05/21");
      script_set_attribute(attribute:"plugin_publication_date", value:"2020/05/22");
      script_set_attribute(attribute:"generated_plugin", value:"current");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 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:"pdns-recursor", reference:"4.1.11-1+deb10u1")) 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");
    

The Hacker News

idTHN:B16A54F3A6063EA035782D8584261F00
last seen2020-05-20
modified2020-05-20
published2020-05-20
reporterThe Hacker News
sourcehttps://thehackernews.com/2020/05/dns-server-ddos-attack.html
titleNew DNS Vulnerability Lets Attackers Launch Large-Scale DDoS Attacks