CVE-2017-11823 : Détail

CVE-2017-11823

6.7
/
Moyen
73.12%V3
Local
2017-10-13
13h00 +00:00
2024-09-17
03h14 +00:00
CVE.org
NVD
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Descriptions du CVE

The Microsoft Device Guard on Microsoft Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016 allows a security feature bypass by the way it handles Windows PowerShell sessions, aka "Microsoft Windows Security Feature Bypass".

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

Métriques

Métriques Score Gravité CVSS Vecteur Source
V3.0 6.7 MEDIUM CVSS:3.0/AV:L/AC:L/PR:H/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.

High

The attacker is authorized with (i.e. requires) privileges that provide significant (e.g. administrative) control over the vulnerable component that could affect component-wide settings and files.

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.

Score EPSS

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.

Percentile EPSS

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 : 42997

Date de publication : 2017-10-16 22h00 +00:00
Auteur : Google Security Research
EDB Vérifié : Yes

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1328 Windows: WLDP/MSHTML CLSID UMCI Bypass Platform: Windows 10 S (thought should be anything with UMCI) Class: Security Feature Bypass Summary: The enlightened lockdown policy check for COM Class instantiation can be bypassed in MSHTML hosts leading to arbitrary code execution on a system with UMCI enabled (e.g. Device Guard) Description: Scripting hosts are supposed to check against the Windows Lockdown Policy (WLDP) before instantiating arbitrary COM classes. This is typically done by calling WldpIsClassInApprovedList from WLDP.DLL before instantiating any COM class. For example in the case of JScript’s ActiveXObject the ProgID is passed to CLSIDFromProgID by the script host and the resulting CLSID is passed to WLDP to determine what’s allowed. It’s possible to circumvent this check by using the COM TreatAs key to redirect one of the limited (8) allowed CLSIDs to an arbitrary class and get it instantiated. However you can’t do this using ActiveXObject as CLSIDFromProgID will return the resulting CLSID from looking up TreatAs. That said there is a race condition here. However in an MSHTML Local Machine Zone scenario you can bypass it by using an OBJECT tag. In this case MSHTML parses the classid attribute and checks that CLSID against WLDP. It then proceeds to create it using CoCreateInstance which follows TreatAs and creates a different object. This does require modification of the registry to work, but I think that’s in scope. The reason I’m reporting this one is I think it’s a bug in MSHTML, rather than in an application you can easily block (at least if you want to disable Proof of Concept: I’ve provided a PoC is two files, a text file to set-up the registry and a HTML file. The registry file is in the REGINI format which allows it to work on Win10S as while reg.exe and regedit.exe are blocked regini.exe isn’t. The HTML file can be run inside IE or my prefered option HTML Help. You could even make the PoC file a CHM but I didn’t. The PoC can bootstrap things like untrusted .NET but for simplicity it doesn’t. 1) Unpack the PoC and ensure the HTML file does NOT have MOTW. 2) From the explorer Run dialog execute “regini path\to\keys.txt” 3) Execute the HTML file from the Run dialog using “hh path\to\shell.html” Expected Result: The class creation should fail. Observed Result: The class creation succeeded and the HTML file executed notepad. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/42997.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_server_2016 >> Version *

Références

http://www.securitytracker.com/id/1039526
Tags : vdb-entry, x_refsource_SECTRACK
https://www.exploit-db.com/exploits/42997/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securityfocus.com/bid/101102
Tags : vdb-entry, x_refsource_BID