Vulnerabilities > CVE-2018-16949 - Resource Exhaustion vulnerability in multiple products

047910
CVSS 5.0 - MEDIUM
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
NONE
Availability impact
PARTIAL
network
low complexity
openafs
debian
CWE-400
nessus
NVD
Published: 2018-09-12
Updated: 2019-03-07

Summary

An issue was discovered in OpenAFS before 1.6.23 and 1.8.x before 1.8.2. Several data types used as RPC input variables were implemented as unbounded array types, limited only by the inherent 32-bit length field to 4 GB. An unauthenticated attacker could send, or claim to send, large input values and consume server resources waiting for those inputs, denying service to other valid connections.

Vulnerable Configurations

Part Description Count
Application
Openafs
194
OS
Debian
2

Common Weakness Enumeration (CWE)

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 familyDebian Local Security Checks
    NASL idDEBIAN_DSA-4302.NASL
    descriptionSeveral vulnerabilities were discovered in openafs, an implementation of the distributed filesystem AFS. The Common Vulnerabilities and Exposures project identifies the following problems : - CVE-2018-16947 Jeffrey Altman reported that the backup tape controller (butc) process does accept incoming RPCs but does not require (or allow for) authentication of those RPCs, allowing an unauthenticated attacker to perform volume operations with administrator credentials. - CVE-2018-16948 Mark Vitale reported that several RPC server routines do not fully initialize output variables, leaking memory contents (from both the stack and the heap) to the remote caller for otherwise-successful RPCs. - CVE-2018-16949 Mark Vitale reported that an unauthenticated attacker can consume large amounts of server memory and network bandwidth via specially crafted requests, resulting in denial of service to legitimate clients.
    last seen2020-06-01
    modified2020-06-02
    plugin id117675
    published2018-09-25
    reporterThis script is Copyright (C) 2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/117675
    titleDebian DSA-4302-1 : openafs - security update
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from Debian Security Advisory DSA-4302. The text 
# itself is copyright (C) Software in the Public Interest, Inc.
#

include("compat.inc");

if (description)
{
  script_id(117675);
  script_version("1.4");
  script_cvs_date("Date: 2018/11/20 11:04:16");

  script_cve_id("CVE-2018-16947", "CVE-2018-16948", "CVE-2018-16949");
  script_xref(name:"DSA", value:"4302");

  script_name(english:"Debian DSA-4302-1 : openafs - 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:
"Several vulnerabilities were discovered in openafs, an implementation
of the distributed filesystem AFS. The Common Vulnerabilities and
Exposures project identifies the following problems :

  - CVE-2018-16947
    Jeffrey Altman reported that the backup tape controller
    (butc) process does accept incoming RPCs but does not
    require (or allow for) authentication of those RPCs,
    allowing an unauthenticated attacker to perform volume
    operations with administrator credentials.

  - CVE-2018-16948
    Mark Vitale reported that several RPC server routines do
    not fully initialize output variables, leaking memory
    contents (from both the stack and the heap) to the
    remote caller for otherwise-successful RPCs.

  - CVE-2018-16949
    Mark Vitale reported that an unauthenticated attacker
    can consume large amounts of server memory and network
    bandwidth via specially crafted requests, resulting in
    denial of service to legitimate clients."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=908616"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://security-tracker.debian.org/tracker/CVE-2018-16947"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://security-tracker.debian.org/tracker/CVE-2018-16948"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://security-tracker.debian.org/tracker/CVE-2018-16949"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://security-tracker.debian.org/tracker/source-package/openafs"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/stretch/openafs"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://www.debian.org/security/2018/dsa-4302"
  );
  script_set_attribute(
    attribute:"solution", 
    value:
"Upgrade the openafs packages.

For the stable distribution (stretch), these problems have been fixed
in version 1.6.20-2+deb9u2."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:9.0");

  script_set_attribute(attribute:"patch_publication_date", value:"2018/09/23");
  script_set_attribute(attribute:"plugin_publication_date", value:"2018/09/25");
  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:"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:"9.0", prefix:"libafsauthent1", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"libafsrpc1", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"libkopenafs1", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"libopenafs-dev", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"libpam-openafs-kaserver", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"openafs-client", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"openafs-dbserver", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"openafs-doc", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"openafs-fileserver", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"openafs-fuse", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"openafs-kpasswd", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"openafs-krb5", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"openafs-modules-dkms", reference:"1.6.20-2+deb9u2")) flag++;
if (deb_check(release:"9.0", prefix:"openafs-modules-source", reference:"1.6.20-2+deb9u2")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_hole(port:0, extra:deb_report_get());
  else security_hole(0);
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");
  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DLA-1513.NASL
    descriptionSeveral security vulnerabilities were discovered in OpenAFS, a distributed file system. CVE-2018-16947 The backup tape controller process accepts incoming RPCs but does not require (or allow for) authentication of those RPCs. Handling those RPCs results in operations being performed with administrator credentials, including dumping/restoring volume contents and manipulating the backup database. CVE-2018-16948 Several RPC server routines did not fully initialize their output variables before returning, leaking memory contents from both the stack and the heap. Because the OpenAFS cache manager functions as an Rx server for the AFSCB service, clients are also susceptible to information leakage. CVE-2018-16949 Several data types used as RPC input variables were implemented as unbounded array types, limited only by the inherent 32-bit length field to 4GB. An unauthenticated attacker could send, or claim to send, large input values and consume server resources waiting for those inputs, denying service to other valid connections. For Debian 8
    last seen2020-06-01
    modified2020-06-02
    plugin id117640
    published2018-09-24
    reporterThis script is Copyright (C) 2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/117640
    titleDebian DLA-1513-1 : openafs security update
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Debian Security Advisory DLA-1513-1. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include("compat.inc");

if (description)
{
  script_id(117640);
  script_version("1.2");
  script_cvs_date("Date: 2018/11/20 11:04:16");

  script_cve_id("CVE-2018-16947", "CVE-2018-16948", "CVE-2018-16949");

  script_name(english:"Debian DLA-1513-1 : openafs security update");
  script_summary(english:"Checks dpkg output for the updated packages.");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Debian host is missing a security update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Several security vulnerabilities were discovered in OpenAFS, a
distributed file system.

CVE-2018-16947

The backup tape controller process accepts incoming RPCs but does not
require (or allow for) authentication of those RPCs. Handling those
RPCs results in operations being performed with administrator
credentials, including dumping/restoring volume contents and
manipulating the backup database.

CVE-2018-16948

Several RPC server routines did not fully initialize their output
variables before returning, leaking memory contents from both the
stack and the heap. Because the OpenAFS cache manager functions as an
Rx server for the AFSCB service, clients are also susceptible to
information leakage.

CVE-2018-16949

Several data types used as RPC input variables were implemented as
unbounded array types, limited only by the inherent 32-bit length
field to 4GB. An unauthenticated attacker could send, or claim to
send, large input values and consume server resources waiting for
those inputs, denying service to other valid connections.

For Debian 8 'Jessie', these problems have been fixed in version
1.6.9-2+deb8u8.

We recommend that you upgrade your openafs packages.

NOTE: Tenable Network Security has extracted the preceding description
block directly from the DLA 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://lists.debian.org/debian-lts-announce/2018/09/msg00024.html"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/jessie/openafs"
  );
  script_set_attribute(attribute:"solution", value:"Upgrade the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libafsauthent1");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libafsrpc1");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libkopenafs1");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libopenafs-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:libpam-openafs-kaserver");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs-client");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs-dbg");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs-dbserver");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs-fileserver");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs-fuse");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs-kpasswd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs-krb5");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs-modules-dkms");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:openafs-modules-source");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:8.0");

  script_set_attribute(attribute:"patch_publication_date", value:"2018/09/21");
  script_set_attribute(attribute:"plugin_publication_date", value:"2018/09/24");
  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:"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:"8.0", prefix:"libafsauthent1", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"libafsrpc1", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"libkopenafs1", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"libopenafs-dev", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"libpam-openafs-kaserver", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"openafs-client", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"openafs-dbg", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"openafs-dbserver", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"openafs-doc", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"openafs-fileserver", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"openafs-fuse", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"openafs-kpasswd", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"openafs-krb5", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"openafs-modules-dkms", reference:"1.6.9-2+deb8u8")) flag++;
if (deb_check(release:"8.0", prefix:"openafs-modules-source", reference:"1.6.9-2+deb8u8")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_hole(port:0, extra:deb_report_get());
  else security_hole(0);
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");

References