Vulnerabilities > CVE-2020-9839 - Race Condition vulnerability in Apple products

047910
CVSS 7.0 - HIGH
Attack vector
LOCAL
Attack complexity
HIGH
Privileges required
NONE
Confidentiality impact
HIGH
Integrity impact
HIGH
Availability impact
HIGH
local
high complexity
apple
CWE-362
nessus

Summary

A race condition was addressed with improved state handling. This issue is fixed in iOS 13.5 and iPadOS 13.5, macOS Catalina 10.15.5, tvOS 13.4.5, watchOS 6.2.5. An application may be able to gain elevated privileges.

Vulnerable Configurations

Part Description Count
OS
Apple
540

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Leveraging Race Conditions
    This attack targets a race condition occurring when multiple processes access and manipulate the same resource concurrently and the outcome of the execution depends on the particular order in which the access takes place. The attacker can leverage a race condition by "running the race", modifying the resource and modifying the normal execution flow. For instance a race condition can occur while accessing a file, the attacker can trick the system by replacing the original file with his version and cause the system to read the malicious 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 familyMacOS X Local Security Checks
NASL idMACOS_HT211170.NASL
descriptionThe remote host is running a version of macOS / Mac OS X that is 10.15.x prior to 10.15.5, 10.13.x prior to 10.13.6 Security Update 2020-003, 10.14.x prior to 10.14.6 Security Update 2020-003. It is, therefore, affected by multiple vulnerabilities: - In ksh version 20120801, a flaw was found in the way it evaluates certain environment variables. An attacker could use this flaw to override or bypass environment restrictions to execute shell commands. Services and applications that allow remote unauthenticated attackers to provide one of those environment variables could allow them to exploit this issue remotely. (CVE-2019-14868) - In Zsh before 5.8, attackers able to execute commands can regain privileges dropped by the --no-PRIVILEGED option. Zsh fails to overwrite the saved uid, so the original privileges can be restored by executing MODULE_PATH=/dir/with/module zmodload with a module that calls setuid(). (CVE-2019-20044) - An out-of-bounds read was addressed with improved input validation. This issue is fixed in iOS 13.3.1 and iPadOS 13.3.1, macOS Catalina 10.15.3, tvOS 13.3.1, watchOS 6.1.2. Processing a maliciously crafted image may lead to arbitrary code execution. (CVE-2020-3878) Note that Nessus has not tested for this issue but has instead relied only on the operating system
last seen2020-06-12
modified2020-05-28
plugin id136930
published2020-05-28
reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
sourcehttps://www.tenable.com/plugins/nessus/136930
titlemacOS 10.15.x < 10.15.5 / 10.14.x < 10.14.6 Security Update 2020-003 / 10.13.x < 10.13.6 Security Update 2020-003
code
#
# (C) Tenable Network Security, Inc.
#

include('compat.inc');

if (description)
{
  script_id(136930);
  script_version("1.6");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/07/17");

  script_cve_id(
    "CVE-2019-14868",
    "CVE-2019-20044",
    "CVE-2020-3878",
    "CVE-2020-3882",
    "CVE-2020-9771",
    "CVE-2020-9772",
    "CVE-2020-9788",
    "CVE-2020-9789",
    "CVE-2020-9790",
    "CVE-2020-9791",
    "CVE-2020-9792",
    "CVE-2020-9793",
    "CVE-2020-9794",
    "CVE-2020-9795",
    "CVE-2020-9797",
    "CVE-2020-9804",
    "CVE-2020-9808",
    "CVE-2020-9809",
    "CVE-2020-9811",
    "CVE-2020-9812",
    "CVE-2020-9813",
    "CVE-2020-9814",
    "CVE-2020-9815",
    "CVE-2020-9816",
    "CVE-2020-9817",
    "CVE-2020-9821",
    "CVE-2020-9822",
    "CVE-2020-9824",
    "CVE-2020-9825",
    "CVE-2020-9826",
    "CVE-2020-9827",
    "CVE-2020-9828",
    "CVE-2020-9830",
    "CVE-2020-9831",
    "CVE-2020-9832",
    "CVE-2020-9833",
    "CVE-2020-9834",
    "CVE-2020-9837",
    "CVE-2020-9839",
    "CVE-2020-9841",
    "CVE-2020-9842",
    "CVE-2020-9844",
    "CVE-2020-9847",
    "CVE-2020-9851",
    "CVE-2020-9852",
    "CVE-2020-9855",
    "CVE-2020-9856",
    "CVE-2020-9857"
  );
  script_xref(name:"APPLE-SA", value:"HT211170");
  script_xref(name:"APPLE-SA", value:"APPLE-SA-2020-05-18");
  script_xref(name:"IAVA", value:"2020-A-0227-S");

  script_name(english:"macOS 10.15.x < 10.15.5 / 10.14.x < 10.14.6 Security Update 2020-003 / 10.13.x < 10.13.6 Security Update 2020-003");

  script_set_attribute(attribute:"synopsis", value:
"The remote host is missing a macOS update that fixes multiple vulnerabilities");
  script_set_attribute(attribute:"description", value:
"The remote host is running a version of macOS / Mac OS X that is 10.15.x prior to 10.15.5, 10.13.x prior to 10.13.6
Security Update 2020-003, 10.14.x prior to 10.14.6 Security Update 2020-003. It is, therefore, affected by multiple
vulnerabilities:

  - In ksh version 20120801, a flaw was found in the way it
    evaluates certain environment variables. An attacker
    could use this flaw to override or bypass environment
    restrictions to execute shell commands. Services and
    applications that allow remote unauthenticated attackers
    to provide one of those environment variables could
    allow them to exploit this issue remotely.
    (CVE-2019-14868)

  - In Zsh before 5.8, attackers able to execute commands
    can regain privileges dropped by the --no-PRIVILEGED
    option. Zsh fails to overwrite the saved uid, so the
    original privileges can be restored by executing
    MODULE_PATH=/dir/with/module zmodload with a module that
    calls setuid(). (CVE-2019-20044)

  - An out-of-bounds read was addressed with improved input
    validation. This issue is fixed in iOS 13.3.1 and iPadOS
    13.3.1, macOS Catalina 10.15.3, tvOS 13.3.1, watchOS
    6.1.2. Processing a maliciously crafted image may lead
    to arbitrary code execution. (CVE-2020-3878)

Note that Nessus has not tested for this issue but has instead relied only on the operating system's self-reported
version number.");
  script_set_attribute(attribute:"see_also", value:"https://support.apple.com/en-us/HT211170");
  script_set_attribute(attribute:"solution", value:
"Upgrade to macOS 10.15.5 / 10.14.x < 10.14.6 Security Update 2020-003 / 10.13.x < 10.13.6 Security Update 2020-003 or
later");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/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:N/UI:R/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:"cvss_score_source", value:"CVE-2020-9852");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/02/24");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/05/18");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/05/28");

  script_set_attribute(attribute:"plugin_type", value:"combined");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:apple:mac_os_x");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:apple:macos");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"MacOS X Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl", "os_fingerprint.nasl");
  script_require_ports("Host/MacOSX/Version", "Host/OS");

  exit(0);
}

include('vcf.inc');
include('lists.inc');
include('vcf_extras_apple.inc'); 

app_info = vcf::apple::macos::get_app_info();

constraints = [
  { 'max_version' : '10.15.4', 'min_version' : '10.15', 'fixed_build' : '19F96', 'fixed_display' : 'macOS Catalina 10.15.5' },
  { 'max_version' : '10.13.6', 'min_version' : '10.13', 'fixed_build' : '17G13033', 'fixed_display' : '10.13.6 Security Update 2020-003' },
  { 'max_version' : '10.14.6', 'min_version' : '10.14', 'fixed_build' : '18G5033', 'fixed_display' : '10.14.6 Security Update 2020-003' }
];

vcf::apple::macos::check_version_and_report(app_info:app_info, constraints:constraints, severity:SECURITY_HOLE);