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CVE-2018-8584 : Détail

CVE-2018-8584

7.8
/
HIGH
0.23%V3
Local
2018-11-14 00:00 +00:00
2019-01-10 09:57 +00:00
CVE.org
NVD

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Descriptions

An elevation of privilege vulnerability exists when Windows improperly handles calls to Advanced Local Procedure Call (ALPC), aka "Windows ALPC Elevation of Privilege Vulnerability." This affects Windows Server 2016, Windows 10, Windows Server 2019, Windows 10 Servers.

Informations

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state.

Metrics

Metric Score Sévérité CVSS Vecteur Source
V3.0 7.8 HIGH CVSS:3.0/AV:L/AC:L/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.

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.

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 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C [email protected]

EPSS

EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.

EPSS Score

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

EPSS Percentile

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.
EPSS First.org

Informations sur l'Exploit

Exploit Database EDB-ID : 46104

Date de publication : 2019-01-08 23:00 +00:00
Auteur : Google Security Research
EDB Vérifié : Yes

Windows: DSSVC CheckFilePermission Arbitrary File Delete EoP Platform: Windows 10 1803 and 1809. Class: Elevation of Privilege Security Boundary (per Windows Security Service Criteria): User boundary NOTE: This is one of multiple issues I’m reporting in the same service. While I’ve tried to ensure all the bugs are effectively orthogonal from each other it’s possible that fixes for one thing might affect others. I’ve also not reported every possible problem with the service as at some point I had to stop. I’ve not determined if any of these issues could be abusable from a sandbox, most of the issues almost certainly can’t be due to the requirements for arbitrary file symlinks but it’s not impossible. Summary: The Data Sharing Service doesn’t has a TOCTOU in PolicyChecker::CheckFilePermission resulting in an arbitrary file deletion. Description: In many different places the DSSVC calls PolicyChecker::CheckFilePermission to ensure the calling user has permission to open a file with a certain set of access rights. This function has an unusual behavior, specifically it passes OPEN_ALWAYS as the disposition to CreateFile even if the code expects the file to already exist. The OPEN_ALWAYS disposition will create a file if it doesn’t exist, to handle the the code checks whether GetLastError() is 0, if it is then it assumes the file is new and so will call DeleteFile on the path. This has a big problem, there’s a TOCTOU in that the path passed to CreateFile doesn’t need to refer to the same file that’s passed to DeleteFile. For example when this method is called in DSSCreateSharedFileTokenEx it’s using the path supplied by the user almost directly. One way of exploiting this would be to specify a path with a mount point in it, then between the call to CreateFile and DeleteFile change the mount point to point somewhere else. However, there’s an easier way, as CreateFile is called under impersonation and DeleteFile is not an attacker could just setup a per-user C: redirection to force the CreateFile call to open a new file in an arbitrary directory, then when DeleteFile is called it’ll be out of the impersonation so will use the system supplied C: drive. Fixing wise you should probably reopen the original file for DELETE access then use the native APIs to delete the file by handle. Also if the file is expected to exist you perhaps should have a flag passed which indicates to use OPEN_EXISTING instead of OPEN_ALWAYS an not try and delete the file anyway. Proof of Concept: I’ve provided a PoC as a C# project. 1) Compile the C# project. It’ll need to pull NtApiDotNet from NuGet to build. 2) Execute the PoC passing the path to a file the user can’t delete on the command line (but can be deleted by SYSTEM). Expected Result: The call to DSOpenSharedFile fails and the file isn’t deleted. Observed Result: The file specified is deleted. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/46104.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_10 >> Version 1803

Microsoft>>Windows_10 >> Version 1809

Microsoft>>Windows_server_2016 >> Version -

Microsoft>>Windows_server_2016 >> Version 1709

Microsoft>>Windows_server_2016 >> Version 1803

Microsoft>>Windows_server_2019 >> Version -

References

http://www.securitytracker.com/id/1042119
Tags : vdb-entry, x_refsource_SECTRACK
https://www.exploit-db.com/exploits/46104/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securityfocus.com/bid/105808
Tags : vdb-entry, x_refsource_BID

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