Vulnerabilities > CVE-2017-8806 - Link Following vulnerability in Postgresql

047910
CVSS 5.5 - MEDIUM
Attack vector
LOCAL
Attack complexity
LOW
Privileges required
LOW
Confidentiality impact
NONE
Integrity impact
HIGH
Availability impact
NONE
local
low complexity
postgresql
CWE-59
nessus
NVD
Published: 2017-11-13
Updated: 2024-11-21

Summary

The Debian pg_ctlcluster, pg_createcluster, and pg_upgradecluster scripts, as distributed in the Debian postgresql-common package before 181+deb9u1 for PostgreSQL (and other packages related to Debian and Ubuntu), handled symbolic links insecurely, which could result in local denial of service by overwriting arbitrary files.

Vulnerable Configurations

Part Description Count
Application
Postgresql
1
OS
Canonical
4
OS
Debian
2

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Symlink Attack
    An attacker positions a symbolic link in such a manner that the targeted user or application accesses the link's endpoint, assuming that it is accessing a file with the link's name. The endpoint file may be either output or input. If the file is output, the result is that the endpoint is modified, instead of a file at the intended location. Modifications to the endpoint file may include appending, overwriting, corrupting, changing permissions, or other modifications. In some variants of this attack the attacker may be able to control the change to a file while in other cases they cannot. The former is especially damaging since the attacker may be able to grant themselves increased privileges or insert false information, but the latter can also be damaging as it can expose sensitive information or corrupt or destroy vital system or application files. Alternatively, the endpoint file may serve as input to the targeted application. This can be used to feed malformed input into the target or to cause the target to process different information, possibly allowing the attacker to control the actions of the target or to cause the target to expose information to the attacker. Moreover, the actions taken on the endpoint file are undertaken with the permissions of the targeted user or application, which may exceed the permissions that the attacker would normally have.
  • 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.
  • Manipulating Input to File System Calls
    An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.

Nessus

  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DSA-4029.NASL
    descriptionIt was discovered that the pg_ctlcluster, pg_createcluster and pg_upgradecluster commands handled symbolic links insecurely which could result in local denial of service by overwriting arbitrary files.
    last seen2020-06-01
    modified2020-06-02
    plugin id104485
    published2017-11-10
    reporterThis script is Copyright (C) 2017-2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/104485
    titleDebian DSA-4029-1 : postgresql-common - security update
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from Debian Security Advisory DSA-4029. The text 
# itself is copyright (C) Software in the Public Interest, Inc.
#

include("compat.inc");

if (description)
{
  script_id(104485);
  script_version("3.5");
  script_cvs_date("Date: 2018/11/10 11:49:38");

  script_cve_id("CVE-2017-8806");
  script_xref(name:"DSA", value:"4029");

  script_name(english:"Debian DSA-4029-1 : postgresql-common - 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:
"It was discovered that the pg_ctlcluster, pg_createcluster and
pg_upgradecluster commands handled symbolic links insecurely which
could result in local denial of service by overwriting arbitrary
files."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/jessie/postgresql-common"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/stretch/postgresql-common"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://www.debian.org/security/2017/dsa-4029"
  );
  script_set_attribute(
    attribute:"solution", 
    value:
"Upgrade the postgresql-common packages.

For the oldstable distribution (jessie), this problem has been fixed
in version 9.4+165+deb8u3.

For the stable distribution (stretch), this problem has been fixed in
version 9.6+181+deb9u1."
  );
  script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:N/I:P/A:P");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:postgresql-common");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:8.0");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:9.0");

  script_set_attribute(attribute:"patch_publication_date", value:"2017/11/09");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/11/10");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2017-2018 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:"postgresql", reference:"9.4+165+deb8u3")) flag++;
if (deb_check(release:"8.0", prefix:"postgresql-client", reference:"9.4+165+deb8u3")) flag++;
if (deb_check(release:"8.0", prefix:"postgresql-contrib", reference:"9.4+165+deb8u3")) flag++;
if (deb_check(release:"8.0", prefix:"postgresql-doc", reference:"9.4+165+deb8u3")) flag++;
if (deb_check(release:"9.0", prefix:"postgresql", reference:"9.6+181+deb9u1")) flag++;
if (deb_check(release:"9.0", prefix:"postgresql-all", reference:"9.6+181+deb9u1")) flag++;
if (deb_check(release:"9.0", prefix:"postgresql-client", reference:"9.6+181+deb9u1")) flag++;
if (deb_check(release:"9.0", prefix:"postgresql-contrib", reference:"9.6+181+deb9u1")) flag++;
if (deb_check(release:"9.0", prefix:"postgresql-doc", reference:"9.6+181+deb9u1")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_note(port:0, extra:deb_report_get());
  else security_note(0);
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");
  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DLA-1169.NASL
    descriptionA security vulnerability has been found in postgresql-common, Debian
    last seen2020-03-17
    modified2017-11-13
    plugin id104502
    published2017-11-13
    reporterThis script is Copyright (C) 2017-2020 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/104502
    titleDebian DLA-1169-1 : postgresql-common 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-1169-1. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include("compat.inc");

if (description)
{
  script_id(104502);
  script_version("3.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/03/12");

  script_name(english:"Debian DLA-1169-1 : postgresql-common 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:
"A security vulnerability has been found in postgresql-common, Debian's
PostgreSQL database cluster management tools.

CVE-2017-8806

It was discovered that the pg_ctlcluster, pg_createcluster and
pg_upgradecluster commands handled symbolic links insecurely which
could result in local denial of service by overwriting arbitrary
files.

For Debian 7 'Wheezy', these problems have been fixed in version
134wheezy6.

We recommend that you upgrade your postgresql-common 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/2017/11/msg00014.html"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/wheezy/postgresql-common"
  );
  script_set_attribute(attribute:"solution", value:"Upgrade the affected packages.");
  script_set_attribute(attribute:"risk_factor", value:"High");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:postgresql");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:postgresql-client");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:postgresql-client-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:postgresql-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:postgresql-contrib");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:postgresql-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:postgresql-server-dev-all");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:7.0");

  script_set_attribute(attribute:"patch_publication_date", value:"2017/11/11");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/11/13");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2017-2020 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);
}

# Temp disable
exit(1, 'Temporarily disabled.');

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:"7.0", prefix:"postgresql", reference:"134wheezy6")) flag++;
if (deb_check(release:"7.0", prefix:"postgresql-client", reference:"134wheezy6")) flag++;
if (deb_check(release:"7.0", prefix:"postgresql-client-common", reference:"134wheezy6")) flag++;
if (deb_check(release:"7.0", prefix:"postgresql-common", reference:"134wheezy6")) flag++;
if (deb_check(release:"7.0", prefix:"postgresql-contrib", reference:"134wheezy6")) flag++;
if (deb_check(release:"7.0", prefix:"postgresql-doc", reference:"134wheezy6")) flag++;
if (deb_check(release:"7.0", prefix:"postgresql-server-dev-all", reference:"134wheezy6")) 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 familyUbuntu Local Security Checks
    NASL idUBUNTU_USN-3476-1.NASL
    descriptionDawid Golunski discovered that the postgresql-common pg_ctlcluster script incorrectly handled symlinks. A local attacker could possibly use this issue to escalate privileges. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2016-1255) It was discovered that the postgresql-common helper scripts incorrectly handled symlinks. A local attacker could possibly use this issue to escalate privileges. (CVE-2017-8806). 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 seen2020-06-01
    modified2020-06-02
    plugin id104496
    published2017-11-10
    reporterUbuntu Security Notice (C) 2017-2019 Canonical, Inc. / NASL script (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/104496
    titleUbuntu 14.04 LTS / 16.04 LTS / 17.04 / 17.10 : postgresql-common vulnerabilities (USN-3476-1)
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-3476-1. 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(104496);
  script_version("3.8");
  script_cvs_date("Date: 2019/09/18 12:31:47");

  script_cve_id("CVE-2016-1255", "CVE-2017-8806");
  script_xref(name:"USN", value:"3476-1");

  script_name(english:"Ubuntu 14.04 LTS / 16.04 LTS / 17.04 / 17.10 : postgresql-common vulnerabilities (USN-3476-1)");
  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:
"Dawid Golunski discovered that the postgresql-common pg_ctlcluster
script incorrectly handled symlinks. A local attacker could possibly
use this issue to escalate privileges. This issue only affected Ubuntu
14.04 LTS and Ubuntu 16.04 LTS. (CVE-2016-1255)

It was discovered that the postgresql-common helper scripts
incorrectly handled symlinks. A local attacker could possibly use this
issue to escalate privileges. (CVE-2017-8806).

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/3476-1/"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Update the affected postgresql-common 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_cvss3_base_vector("CVSS:3.0/AV:L/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:"exploit_available", value:"false");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:postgresql-common");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:14.04");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:17.04");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:17.10");

  script_set_attribute(attribute:"vuln_publication_date", value:"2017/11/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2017/11/09");
  script_set_attribute(attribute:"plugin_publication_date", value:"2017/11/10");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"Ubuntu Security Notice (C) 2017-2019 Canonical, Inc. / NASL script (C) 2017-2019 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:"^(14\.04|16\.04|17\.04|17\.10)$", string:release)) audit(AUDIT_OS_NOT, "Ubuntu 14.04 / 16.04 / 17.04 / 17.10", "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:"14.04", pkgname:"postgresql-common", pkgver:"154ubuntu1.1")) flag++;
if (ubuntu_check(osver:"16.04", pkgname:"postgresql-common", pkgver:"173ubuntu0.1")) flag++;
if (ubuntu_check(osver:"17.04", pkgname:"postgresql-common", pkgver:"179ubuntu0.1")) flag++;
if (ubuntu_check(osver:"17.10", pkgname:"postgresql-common", pkgver:"184ubuntu1.1")) 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, "postgresql-common");
}

References