Vulnerabilities > CVE-2019-7307 - Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in Apport Project Apport

047910
CVSS 7.0 - HIGH
Attack vector
LOCAL
Attack complexity
HIGH
Privileges required
LOW
Confidentiality impact
HIGH
Integrity impact
HIGH
Availability impact
HIGH
local
high complexity
apport-project
CWE-367
nessus
NVD
Published: 2019-08-29
Updated: 2024-11-21

Summary

Apport before versions 2.14.1-0ubuntu3.29+esm1, 2.20.1-0ubuntu2.19, 2.20.9-0ubuntu7.7, 2.20.10-0ubuntu27.1, 2.20.11-0ubuntu5 contained a TOCTTOU vulnerability when reading the users ~/.apport-ignore.xml file, which allows a local attacker to replace this file with a symlink to any other file on the system and so cause Apport to include the contents of this other file in the resulting crash report. The crash report could then be read by that user either by causing it to be uploaded and reported to Launchpad, or by leveraging some other vulnerability to read the resulting crash report, and so allow the user to read arbitrary files on the system.

Vulnerable Configurations

Part Description Count
Application
Apport_Project
4
OS
Canonical
5

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Leveraging Race Conditions via Symbolic Links
    This attack leverages the use of symbolic links (Symlinks) in order to write to sensitive files. An attacker can create a Symlink link to a target file not otherwise accessible to her. When the privileged program tries to create a temporary file with the same name as the Symlink link, it will actually write to the target file pointed to by the attackers' Symlink link. If the attacker can insert malicious content in the temporary file she will be writing to the sensitive file by using the Symlink. The race occurs because the system checks if the temporary file exists, then creates the file. The attacker would typically create the Symlink during the interval between the check and the creation of the temporary file.
  • Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
    This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. The typical example is the file access. The attacker can leverage a file access race condition by "running the race", meaning that he would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the attacker could do something such as replace the file and cause an escalation of privilege.

Nessus

NASL familyUbuntu Local Security Checks
NASL idUBUNTU_USN-4051-1.NASL
descriptionKevin Backhouse discovered a race-condition when reading the user
last seen2020-06-01
modified2020-06-02
plugin id126567
published2019-07-09
reporterUbuntu Security Notice (C) 2019-2020 Canonical, Inc. / NASL script (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/126567
titleUbuntu 16.04 LTS / 18.04 LTS / 18.10 / 19.04 : apport vulnerability (USN-4051-1)
code
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4051-1. 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(126567);
  script_version("1.4");
  script_cvs_date("Date: 2020/01/08");

  script_cve_id("CVE-2019-7307");
  script_xref(name:"USN", value:"4051-1");

  script_name(english:"Ubuntu 16.04 LTS / 18.04 LTS / 18.10 / 19.04 : apport vulnerability (USN-4051-1)");
  script_summary(english:"Checks dpkg output for updated packages.");

  script_set_attribute(
    attribute:"synopsis", 
    value:
"The remote Ubuntu host is missing one or more security-related
patches."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Kevin Backhouse discovered a race-condition when reading the user's
local Apport configuration. This could be used by a local attacker to
cause Apport to include arbitrary files in a resulting crash report.

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/4051-1/"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Update the affected python-apport and / or python3-apport packages."
  );
  script_set_cvss_base_vector("CVSS2#AV:L/AC:M/Au:N/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:L/AC:H/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:canonical:ubuntu_linux:python-apport");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3-apport");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.10");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:19.04");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/08/29");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/07/09");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/07/09");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"Ubuntu Security Notice (C) 2019-2020 Canonical, Inc. / NASL script (C) 2019-2020 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:"^(16\.04|18\.04|18\.10|19\.04)$", string:release)) audit(AUDIT_OS_NOT, "Ubuntu 16.04 / 18.04 / 18.10 / 19.04", "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:"16.04", pkgname:"python-apport", pkgver:"2.20.1-0ubuntu2.19")) flag++;
if (ubuntu_check(osver:"16.04", pkgname:"python3-apport", pkgver:"2.20.1-0ubuntu2.19")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"python-apport", pkgver:"2.20.9-0ubuntu7.7")) flag++;
if (ubuntu_check(osver:"18.04", pkgname:"python3-apport", pkgver:"2.20.9-0ubuntu7.7")) flag++;
if (ubuntu_check(osver:"18.10", pkgname:"python-apport", pkgver:"2.20.10-0ubuntu13.4")) flag++;
if (ubuntu_check(osver:"18.10", pkgname:"python3-apport", pkgver:"2.20.10-0ubuntu13.4")) flag++;
if (ubuntu_check(osver:"19.04", pkgname:"python-apport", pkgver:"2.20.10-0ubuntu27.1")) flag++;
if (ubuntu_check(osver:"19.04", pkgname:"python3-apport", pkgver:"2.20.10-0ubuntu27.1")) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    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, "python-apport / python3-apport");
}

References