CVE-2018-0882 : Detail

CVE-2018-0882

7
/
High
42.38%V3
Local
2018-03-14
17h00 +00:00
2024-09-16
21h03 +00:00
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CVE Descriptions

The Desktop Bridge in Windows 10 1607, 1703, and 1709, Windows Server 2016 and Windows Server, version 1709 allows an elevation of privilege vulnerability due to how the virtual registry is managed, aka "Windows Desktop Bridge Elevation of Privilege Vulnerability". This CVE is unique from CVE-2018-0880.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE Other No informations.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 7 HIGH CVSS:3.0/AV:L/AC:H/PR:L/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.

Local

A vulnerability exploitable with Local access means that the vulnerable component is not bound to the network stack, and the attacker's path is via read/write/execute capabilities. In some cases, the attacker may be logged in locally in order to exploit the vulnerability, otherwise, she may rely on User Interaction to execute a malicious file.

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.

Low

The attacker is authorized with (i.e. requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.

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 6.9 AV:L/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 : 44315

Publication date : 2018-03-19 23h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Windows: Desktop Bridge Virtual Registry NtLoadKey Arbitrary File Read/Write EoP Platform: Windows 1703 (version 1709 seems to have fixed this bug) Class: Elevation of Privilege Summary: The handling of the virtual registry NtLoadKey callback reloads registry hives insecurely leading to arbitrary file creation resulting in EoP. Description: NOTE: This bug seems to have been fixed in 1709, but the fix hasn’t been backported to 1703 (I’ve not checked 1607). I don’t know if the fix was intentional or not, however as (according to https://support.microsoft.com/en-gb/help/13853/windows-lifecycle-fact-sheet) 1703 should be supported until at least September 2018 this should be something you’d consider fixing. The desktop bridge functionality introduced in Anniversary edition allows an application to set up a virtual registry to add changes to system hives and user hives without actually modifying the real hives. This is implemented through the normal registry callback functionality. One of the callbacks implemented is to handle the NtLoadKey system call (VrpPreLoadKey). On 1703 it doesn’t check for the Application Key flag, but then recalls ZwLoadKey with the arguments passed by the user mode caller. This effectively allows you to circumvent the requirement for SeRestorePrivilege as will also create a new hive file with kernel privileges in the context of the current user. This is a trivial EoP by dropping a arbitrary file to disk then getting system privileges. Proof of Concept: I’ve provided a PoC as a C# project. In order for the exploit to work you need a copy of the Get Office/My Office application installed (I tested with version 17.8830.7600.0). It could be any desktop bridge application however as you just need to run a program inside the container. Again I’ll note that this will only work on 1703 as the code seems to have been fixed in 1709. The registry hives files it creates will be locked (we can’t easily unload the hive) until reboot although it’s probably possible to trick the system into failing the load while still creating some files. 1) Compile the C# project. It will need to grab the NtApiDotNet from NuGet to work. 2) Start the Get Office/My Office application 3) Start the poc. It should print that it successfully created the registry files. Expected Result: Loading the registry key should fail. Observed Result: The registry key is loaded and the file test.hiv has been created in the windows folder with full access for the current user. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/44315.zip

Products Mentioned

Configuraton 0

Microsoft>>Windows_10 >> Version -

Microsoft>>Windows_10 >> Version 1607

Microsoft>>Windows_10 >> Version 1703

Microsoft>>Windows_10 >> Version 1709

Microsoft>>Windows_server >> Version 1709

Microsoft>>Windows_server_2016 >> Version -

References

http://www.securityfocus.com/bid/103257
Tags : vdb-entry, x_refsource_BID
http://www.securitytracker.com/id/1040520
Tags : vdb-entry, x_refsource_SECTRACK
https://www.exploit-db.com/exploits/44315/
Tags : exploit, x_refsource_EXPLOIT-DB