CVE-2018-0751 : Detail

CVE-2018-0751

7.1
/
High
Improper Privilege Management
A04-Insecure Design
54.85%V3
Local
2018-01-04
14h00 +00:00
2024-09-16
20h42 +00:00
CVE.org
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CVE Descriptions

The Windows Kernel API in Windows 8.1 and RT 8.1, Windows Server 2012 and R2, Windows 10 Gold, 1511, 1607, 1703 and 1709, Windows Server 2016 and Windows Server, version 1709 allows an elevation of privilege vulnerability due to the way the Kernel API enforces permissions, aka "Windows Elevation of Privilege Vulnerability". This CVE ID is unique from CVE-2018-0752.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-269 Improper Privilege Management
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 7.1 HIGH CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

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.

Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.

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.

None

There is no impact to availability within the impacted component.

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 3.6 AV:L/AC:L/Au:N/C:P/I:P/A:N [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.
EPSS First.org

Exploit information

Exploit Database EDB-ID : 43515

Publication date : 2018-01-10 23h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Windows: NtImpersonateAnonymousToken AC to Non-AC EoP Platform: Windows 10 1703 and 1709 Class: Elevation of Privilege Summary: The check for an AC token when impersonating the anonymous token doesn’t check impersonation token’s security level leading to impersonating a non-AC anonymous token leading to EoP. Description: There's a missing check for impersonation level in NtImpersonateAnonymousToken when considering if the caller is currently an AC. This results in the function falling into the restricted token case if the caller is impersonating a non AC token at identification or below. Some example code is shown highlighting the issue. SeCaptureSubjectContext(&ctx); PACCESS_TOKEN token = ctx.ClientToken; if (!ctx.ClientToken) <--- Should check the token's impersonation level here, and fallback to the PrimaryToken. token = ctx.PrimaryToken; if (token->Flags & 0x4000) { // ... Impersonate AC anonymous token. } else if (!SeTokenIsRestricted(PsReferencePrimaryToken())) { <-- AC PrimaryToken isn't restricted so this check passes // ... Impersonate normal anonymous token. } For example when using a split-token admin you can trivially get the linked token and impersonate that. As an AC token isn't restricted this results in impersonating the normal anonymous token which is arguably less restricted than the AC token in some cases and is certainly less restricted than the anonymous AC token which is normally created using SepGetAnonymousToken. For example you can open objects with a NULL DACL if you can traverse to them or open devices which would normally need the special AC device object flag for traversal across the object namespace. You can also access the anonymous token's device map and modify it, potentially leading to bypass of symbolic link protections in certain cases. Proof of Concept: I’ve provided a PoC as a C# project. The PoC will respawn itself as the Microsoft Edge AC and then execute the exploit. You must run this as a UAC split token admin. Note that this ISN’T a UAC bypass, just that a split-token admin has a trivial way of getting a non-AC token by requesting the linked token. 1) Compile the C# project. It will need to grab the NtApiDotNet from NuGet to work. Ensure the main executable and DLLs are in a user writable location (this is needed to tweak the file permissions for AC). 2) Execute the PoC as normal user level split-token admin. 3) Once complete a dialog should appear indicating the operation is a success. Expected Result: The AC anonymous token is impersonated, or at least an error occurs. Observed Result: The Non-AC anonymous token is impersonated. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/43515.zip

Products Mentioned

Configuraton 0

Microsoft>>Windows_10 >> Version -

Microsoft>>Windows_10 >> Version 1511

Microsoft>>Windows_10 >> Version 1607

Microsoft>>Windows_10 >> Version 1703

Microsoft>>Windows_10 >> Version 1709

Microsoft>>Windows_8.1 >> Version *

Microsoft>>Windows_rt_8.1 >> Version *

Microsoft>>Windows_server_2012 >> Version -

Microsoft>>Windows_server_2012 >> Version r2

Microsoft>>Windows_server_2016 >> Version -

Microsoft>>Windows_server_2016 >> Version 1709

References

https://www.exploit-db.com/exploits/43515/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securityfocus.com/bid/102359
Tags : vdb-entry, x_refsource_BID
http://www.securitytracker.com/id/1040095
Tags : vdb-entry, x_refsource_SECTRACK