Vulnerabilities > CVE-2018-16947 - Improper Authentication vulnerability in multiple products

047910
CVSS 7.5 - HIGH
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
PARTIAL
Integrity impact
PARTIAL
Availability impact
PARTIAL
network
low complexity
openafs
debian
CWE-287
nessus
NVD
Published: 2018-09-12
Updated: 2019-10-03

Summary

An issue was discovered in OpenAFS before 1.6.23 and 1.8.x before 1.8.2. The backup tape controller (butc) 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. For example, an unauthenticated attacker can replace any volume's content with arbitrary data.

Vulnerable Configurations

Part Description Count
Application
Openafs
194
OS
Debian
2

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Authentication Abuse
    An attacker obtains unauthorized access to an application, service or device either through knowledge of the inherent weaknesses of an authentication mechanism, or by exploiting a flaw in the authentication scheme's implementation. In such an attack an authentication mechanism is functioning but a carefully controlled sequence of events causes the mechanism to grant access to the attacker. This attack may exploit assumptions made by the target's authentication procedures, such as assumptions regarding trust relationships or assumptions regarding the generation of secret values. This attack differs from Authentication Bypass attacks in that Authentication Abuse allows the attacker to be certified as a valid user through illegitimate means, while Authentication Bypass allows the user to access protected material without ever being certified as an authenticated user. This attack does not rely on prior sessions established by successfully authenticating users, as relied upon for the "Exploitation of Session Variables, Resource IDs and other Trusted Credentials" attack patterns.
  • Exploiting Trust in Client (aka Make the Client Invisible)
    An attack of this type exploits a programs' vulnerabilities in client/server communication channel authentication and data integrity. It leverages the implicit trust a server places in the client, or more importantly, that which the server believes is the client. An attacker executes this type of attack by placing themselves in the communication channel between client and server such that communication directly to the server is possible where the server believes it is communicating only with a valid client. There are numerous variations of this type of attack.
  • Utilizing REST's Trust in the System Resource to Register Man in the Middle
    This attack utilizes a REST(REpresentational State Transfer)-style applications' trust in the system resources and environment to place man in the middle once SSL is terminated. Rest applications premise is that they leverage existing infrastructure to deliver web services functionality. An example of this is a Rest application that uses HTTP Get methods and receives a HTTP response with an XML document. These Rest style web services are deployed on existing infrastructure such as Apache and IIS web servers with no SOAP stack required. Unfortunately from a security standpoint, there frequently is no interoperable identity security mechanism deployed, so Rest developers often fall back to SSL to deliver security. In large data centers, SSL is typically terminated at the edge of the network - at the firewall, load balancer, or router. Once the SSL is terminated the HTTP request is in the clear (unless developers have hashed or encrypted the values, but this is rare). The attacker can utilize a sniffer such as Wireshark to snapshot the credentials, such as username and password that are passed in the clear once SSL is terminated. Once the attacker gathers these credentials, they can submit requests to the web service provider just as authorized user do. There is not typically an authentication on the client side, beyond what is passed in the request itself so once this is compromised, then this is generally sufficient to compromise the service's authentication scheme.
  • Man in the Middle Attack
    This type of attack targets the communication between two components (typically client and server). The attacker places himself in the communication channel between the two components. Whenever one component attempts to communicate with the other (data flow, authentication challenges, etc.), the data first goes to the attacker, who has the opportunity to observe or alter it, and it is then passed on to the other component as if it was never intercepted. This interposition is transparent leaving the two compromised components unaware of the potential corruption or leakage of their communications. The potential for Man-in-the-Middle attacks yields an implicit lack of trust in communication or identify between two components.

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