Vulnerabilities > CVE-2013-6441 - Permissions, Privileges, and Access Controls vulnerability in Linuxcontainers LXC

047910
CVSS 7.2 - HIGH
Attack vector
LOCAL
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
COMPLETE
Integrity impact
COMPLETE
Availability impact
COMPLETE
local
low complexity
linuxcontainers
CWE-264
nessus
NVD
Published: 2014-02-14
Updated: 2014-02-18

Summary

The lxc-sshd template (templates/lxc-sshd.in) in LXC before 1.0.0.beta2 uses read-write permissions when mounting /sbin/init, which allows local users to gain privileges by modifying the init file.

Vulnerable Configurations

Part Description Count
Application
Linuxcontainers
24

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Accessing, Modifying or Executing Executable Files
    An attack of this type exploits a system's configuration that allows an attacker to either directly access an executable file, for example through shell access; or in a possible worst case allows an attacker to upload a file and then execute it. Web servers, ftp servers, and message oriented middleware systems which have many integration points are particularly vulnerable, because both the programmers and the administrators must be in synch regarding the interfaces and the correct privileges for each interface.
  • Leverage Executable Code in Non-Executable Files
    An attack of this type exploits a system's trust in configuration and resource files, when the executable loads the resource (such as an image file or configuration file) the attacker has modified the file to either execute malicious code directly or manipulate the target process (e.g. application server) to execute based on the malicious configuration parameters. Since systems are increasingly interrelated mashing up resources from local and remote sources the possibility of this attack occurring is high. The attack can be directed at a client system, such as causing buffer overrun through loading seemingly benign image files, as in Microsoft Security Bulletin MS04-028 where specially crafted JPEG files could cause a buffer overrun once loaded into the browser. Another example targets clients reading pdf files. In this case the attacker simply appends javascript to the end of a legitimate url for a pdf (http://www.gnucitizen.org/blog/danger-danger-danger/) http://path/to/pdf/file.pdf#whatever_name_you_want=javascript:your_code_here The client assumes that they are reading a pdf, but the attacker has modified the resource and loaded executable javascript into the client's browser process. The attack can also target server processes. The attacker edits the resource or configuration file, for example a web.xml file used to configure security permissions for a J2EE app server, adding role name "public" grants all users with the public role the ability to use the administration functionality. The server trusts its configuration file to be correct, but when they are manipulated, the attacker gains full control.
  • Blue Boxing
    This type of attack against older telephone switches and trunks has been around for decades. A tone is sent by an adversary to impersonate a supervisor signal which has the effect of rerouting or usurping command of the line. While the US infrastructure proper may not contain widespread vulnerabilities to this type of attack, many companies are connected globally through call centers and business process outsourcing. These international systems may be operated in countries which have not upgraded Telco infrastructure and so are vulnerable to Blue boxing. Blue boxing is a result of failure on the part of the system to enforce strong authorization for administrative functions. While the infrastructure is different than standard current applications like web applications, there are historical lessons to be learned to upgrade the access control for administrative functions.
  • Restful Privilege Elevation
    Rest uses standard HTTP (Get, Put, Delete) style permissions methods, but these are not necessarily correlated generally with back end programs. Strict interpretation of HTTP get methods means that these HTTP Get services should not be used to delete information on the server, but there is no access control mechanism to back up this logic. This means that unless the services are properly ACL'd and the application's service implementation are following these guidelines then an HTTP request can easily execute a delete or update on the server side. The attacker identifies a HTTP Get URL such as http://victimsite/updateOrder, which calls out to a program to update orders on a database or other resource. The URL is not idempotent so the request can be submitted multiple times by the attacker, additionally, the attacker may be able to exploit the URL published as a Get method that actually performs updates (instead of merely retrieving data). This may result in malicious or inadvertent altering of data on the server.
  • Target Programs with Elevated Privileges
    This attack targets programs running with elevated privileges. The attacker would try to leverage a bug in the running program and get arbitrary code to execute with elevated privileges. For instance an attacker would look for programs that write to the system directories or registry keys (such as HKLM, which stores a number of critical Windows environment variables). These programs are typically running with elevated privileges and have usually not been designed with security in mind. Such programs are excellent exploit targets because they yield lots of power when they break. The malicious user try to execute its code at the same level as a privileged system call.

Nessus

  • NASL familyUbuntu Local Security Checks
    NASL idUBUNTU_USN-2104-1.NASL
    descriptionFlorian Sagar discovered that the LXC sshd template set incorrect mount permissions. An attacker could possibly use this flaw to cause privilege escalation on the host. 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 seen2020-03-18
    modified2014-02-13
    plugin id72479
    published2014-02-13
    reporterUbuntu Security Notice (C) 2014-2020 Canonical, Inc. / NASL script (C) 2014-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/72479
    titleUbuntu 13.10 : lxc vulnerability (USN-2104-1)
    code
    #%NASL_MIN_LEVEL 80502
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-2104-1. The text 
# itself is copyright (C) Canonical, Inc. See 
# <http://www.ubuntu.com/usn/>. Ubuntu(R) is a registered 
# trademark of Canonical, Inc.
#

include("compat.inc");

if (description)
{
  script_id(72479);
  script_version("1.10");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/03/12");

  script_cve_id("CVE-2013-6441");
  script_xref(name:"USN", value:"2104-1");

  script_name(english:"Ubuntu 13.10 : lxc vulnerability (USN-2104-1)");
  script_summary(english:"Checks dpkg output for updated package.");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Ubuntu host is missing a security-related patch."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Florian Sagar discovered that the LXC sshd template set incorrect
mount permissions. An attacker could possibly use this flaw to cause
privilege escalation on the host.

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."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://usn.ubuntu.com/2104-1/"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Update the affected lxc-templates package."
  );
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:lxc-templates");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:13.10");

  script_set_attribute(attribute:"vuln_publication_date", value:"2014/02/14");
  script_set_attribute(attribute:"patch_publication_date", value:"2014/02/12");
  script_set_attribute(attribute:"plugin_publication_date", value:"2014/02/13");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"Ubuntu Security Notice (C) 2014-2020 Canonical, Inc. / NASL script (C) 2014-2019 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Ubuntu Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}


include("audit.inc");
include("ubuntu.inc");
include("misc_func.inc");

if ( ! get_kb_item("Host/local_checks_enabled") ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
release = get_kb_item("Host/Ubuntu/release");
if ( isnull(release) ) audit(AUDIT_OS_NOT, "Ubuntu");
release = chomp(release);
if (! preg(pattern:"^(13\.10)$", string:release)) audit(AUDIT_OS_NOT, "Ubuntu 13.10", "Ubuntu " + release);
if ( ! get_kb_item("Host/Debian/dpkg-l") ) 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, "Ubuntu", cpu);

flag = 0;

if (ubuntu_check(osver:"13.10", pkgname:"lxc-templates", pkgver:"1.0.0~alpha1-0ubuntu14.1")) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : ubuntu_report_get()
  );
  exit(0);
}
else
{
  tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "lxc-templates");
}
  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DLA-442.NASL
    descriptionBrief introduction CVE-2013-6441 The template script lxc-sshd used to mount itself as /sbin/init in the container using a writable bind-mount. This update resolved the above issue by using a read-only bind-mount instead preventing any form of potentially accidental damage. CVE-2015-1335 On container startup, lxc sets up the container
    last seen2020-03-17
    modified2016-03-01
    plugin id89042
    published2016-03-01
    reporterThis script is Copyright (C) 2016-2020 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/89042
    titleDebian DLA-442-1 : lxc security update
    code
    #%NASL_MIN_LEVEL 80502
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Debian Security Advisory DLA-442-1. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include("compat.inc");

if (description)
{
  script_id(89042);
  script_version("2.7");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/03/12");

  script_cve_id("CVE-2013-6441", "CVE-2015-1335");
  script_bugtraq_id(65562);

  script_name(english:"Debian DLA-442-1 : lxc 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 update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Brief introduction 

CVE-2013-6441

The template script lxc-sshd used to mount itself as /sbin/init in the
container using a writable bind-mount.

This update resolved the above issue by using a read-only
bind-mount instead preventing any form of potentially
accidental damage.

CVE-2015-1335

On container startup, lxc sets up the container's initial file system
tree by doing a bunch of mounting, guided by the container's
configuration file.

The container config is owned by the admin or user on the
host, so we do not try to guard against bad entries.
However, since the mount target is in the container, it's
possible that the container admin could divert the mount
with symbolic links. This could bypass proper container
startup (i.e. confinement of a root-owned container by the
restrictive apparmor policy, by diverting the required write
to /proc/self/attr/current), or bypass the (path-based)
apparmor policy by diverting, say, /proc to /mnt in the
container.

This update implements a safe_mount() function that prevents
lxc from doing mounts onto symbolic links.

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/2016/02/msg00033.html"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/squeeze-lts/lxc"
  );
  script_set_attribute(attribute:"solution", value:"Upgrade the affected lxc package.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:lxc");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:6.0");

  script_set_attribute(attribute:"patch_publication_date", value:"2016/02/29");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/03/01");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2016-2020 Tenable Network Security, Inc.");
  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:"6.0", prefix:"lxc", reference:"0.7.2-1+deb6u1")) 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 familySuSE Local Security Checks
    NASL idSUSE_11_LXC-140401.NASL
    descriptionThe container framework LXC has been updated to fix various bugs and a security issue : - The sshd template allowed privilege escalation on the host. (CVE-2013-6441) - SLES container time not aligned with host time. (bnc#839653) - SLES container boot takes ages. (bnc#839663) - lxc mounts /dev/pts with wrong options (bnc#869663)
    last seen2020-06-05
    modified2014-05-15
    plugin id74021
    published2014-05-15
    reporterThis script is Copyright (C) 2014-2020 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/74021
    titleSuSE 11.3 Security Update : lxc (SAT Patch Number 9084)
    code
    #%NASL_MIN_LEVEL 80502
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from SuSE 11 update information. The text itself is
# copyright (C) Novell, Inc.
#

if (NASL_LEVEL < 3000) exit(0);

include("compat.inc");

if (description)
{
  script_id(74021);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/04");

  script_cve_id("CVE-2013-6441");

  script_name(english:"SuSE 11.3 Security Update : lxc (SAT Patch Number 9084)");
  script_summary(english:"Checks rpm output for the updated package");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote SuSE 11 host is missing a security update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"The container framework LXC has been updated to fix various bugs and a
security issue :

  - The sshd template allowed privilege escalation on the
    host. (CVE-2013-6441)

  - SLES container time not aligned with host time.
    (bnc#839653)

  - SLES container boot takes ages. (bnc#839663)

  - lxc mounts /dev/pts with wrong options (bnc#869663)"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugzilla.novell.com/show_bug.cgi?id=839653"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugzilla.novell.com/show_bug.cgi?id=839663"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugzilla.novell.com/show_bug.cgi?id=855809"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugzilla.novell.com/show_bug.cgi?id=869663"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"http://support.novell.com/security/cve/CVE-2013-6441.html"
  );
  script_set_attribute(attribute:"solution", value:"Apply SAT patch number 9084.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:suse_linux:11:lxc");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:novell:suse_linux:11");

  script_set_attribute(attribute:"patch_publication_date", value:"2014/04/01");
  script_set_attribute(attribute:"plugin_publication_date", value:"2014/05/15");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2014-2020 Tenable Network Security, Inc.");
  script_family(english:"SuSE Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/cpu", "Host/SuSE/release", "Host/SuSE/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/SuSE/release");
if (isnull(release) || release !~ "^(SLED|SLES)11") audit(AUDIT_OS_NOT, "SuSE 11");
if (!get_kb_item("Host/SuSE/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

cpu = get_kb_item("Host/cpu");
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if (cpu !~ "^i[3-6]86$" && "x86_64" >!< cpu && "s390x" >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "SuSE 11", cpu);

pl = get_kb_item("Host/SuSE/patchlevel");
if (isnull(pl) || int(pl) != 3) audit(AUDIT_OS_NOT, "SuSE 11.3");


flag = 0;
if (rpm_check(release:"SLED11", sp:3, cpu:"i586", reference:"lxc-0.8.0-0.21.6")) flag++;
if (rpm_check(release:"SLED11", sp:3, cpu:"x86_64", reference:"lxc-0.8.0-0.21.6")) flag++;
if (rpm_check(release:"SLES11", sp:3, reference:"lxc-0.8.0-0.21.6")) flag++;


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

References