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CVE-2017-0214 : Détail

CVE-2017-0214

7
/
HIGH
0.05%V3
Local
2017-05-12 12:00 +00:00
2017-08-12 07:57 +00:00
CVE.org
NVD

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Descriptions

Windows COM in Microsoft Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016 allows an elevation privilege vulnerability when Windows fails to properly validate input before loading type libraries, aka "Windows COM Elevation of Privilege Vulnerability". This CVE ID is unique from CVE-2017-0213.

Informations

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE Other No informations.

Metrics

Metric Score Sévérité CVSS Vecteur Source
V3.0 7 HIGH CVSS:3.0/AV:L/AC:H/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.

High

A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected.

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 4.4 AV:L/AC:M/Au:N/C:P/I:P/A:P [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 : 42021

Date de publication : 2017-05-16 22:00 +00:00
Auteur : Google Security Research
EDB Vérifié : Yes

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1112 Windows: Running Object Table Register ROTFLAGS_ALLOWANYCLIENT EoP Platform: Windows 10 10586/14393 not tested 8.1 Update 2 or Windows 7 Class: Elevation of Privilege Summary: By setting an appropriate AppID it’s possible for a normal user process to set a global ROT entry. This can be abused to elevate privileges. Description: NOTE: I’m not sure which part of this chain to really report. As far as I can tell it’s pretty much all by design and fixing the initial vector seems difficult. Perhaps this is only a bug which can be fixed to prevent sandbox escapes? When registering an object in the ROT the default is to only expose that registration to the same user identity on the same desktop/window station. This includes preventing the same user at different ILs (such as between sandbox and normal user) from seeing the same registration. However it could be imagined that you might want to register an entry for all users/contexts so IRunningObjectTable::Register takes a grfFlags parameter with the value ROTFLAGS_ALLOWANYCLIENT which allows the ROT entry to be exposed to all users. The description of this flag indicates it can only be used if the COM process is a Local Service or a RunAs application. In fact there’s an explicit ROTFlags value for the AppID which would grant the privilege to a normal application. Quick testing proves this to be correct, a “normal” application cannot expose the ROT entry to any client as RPCSS does a check that the calling process is allowed to expose the entry. However there are two clear problems with the check. Creating a RunAs COM object in the current session would typically run at the same privilege level as the caller, therefore an application which wanted to abuse this feature could inject code into that process. Secondly while it’s not possible to register a per-user COM object which specifies a RunAs AppID it’s possible to explicitly set the AppID when calling CoInitializeSecurity (either via the GUID or by naming your program to match one which maps to the correct AppID). Therefore in the current implementation effectively any process, including sandboxed ones should be able to register a global ROT entry. What can we do with this? The ROT is mainly used for OLE duties, for example Word and Visual Studio register entries for each document/project open. It would be nice not to rely on this, so instead I’ll abuse another OLE component, which we’ve seen before, the fact that LoadTypeLib will fall back to a moniker if it can’t find the type library file specified. If the file loading fails then LoadTypeLib will effectively call MkParseDisplayName on the passed in string. One of the things MPDN does is try and create a file moniker with the string passed in as an argument. File Monikers have an interesting feature, the COM libraries will check if there’s a registered ROT entry for this file moniker already present, if it is instead of creating a new object it will call IRunningObjectTable::GetObject instead when binding. So as we can register a ROT entry for any user in any context we can provide our own implementation of ITypeLib running inside our process, by registering it against the path to the type library any other process which tries to open that library would instead get our spoofed one, assuming we can force the file open to fail. This is the next key part, looking at the LoadTypeLib implementation the code calls FindTypeLib if this function fails the code will fall back to the moniker route. There’s two opportunities here, firstly CreateFile is called on the path, we could cause this to fail by opening the file with no sharing mode, in theory it should fail. However in practice it doesn’t most type libraries are in system location, if you don’t have the possibility of write permission on the file the OS automatically applies FILE_SHARE_READ which makes it impossible to lock the file in its entirety. Also some TLBs are stored inside a DLL which is then used so this route is out. Instead the other route is more promising, VerifyIsExeOrTlb is called once the file is open to check the type of file to parse. This function tries to load the first 64 bytes and checks for magic signatures. We can cause the read to fail by using the LockFile API to put an exclusive lock on that part of the file. This also has the advantage that it doesn’t affect file mappings so will also work with loaded DLLs. We now can cause any user of a type library to get redirected to our “fake” one without abusing impersonation/symbolic link tricks. How can we use this to our advantage? The final trick is to abuse again the auto-generation of Stubs/Proxies from automation compatible interfaces. If we can get a more privileged process to use our type library when creating a COM stub we can cause a number of memory safety issues such as type confusion, arbitrary memory read/writes and extending the vtable to call arbitrary functions. This is an extremely powerful primitive, as long as you can find a more privileged process which uses a dual automation interface. For example the FlashBroker which is installed on every Win8+ machine is intentionally allowed to be created by sandboxed IE/Edge and uses dual interfaces with auto-generated Stubs. We could abuse for example the BrokerPrefSetExceptionDialogSize and BrokerPrefGetExceptionDialogSize to do arbitrary memory writes. This all works because the stub creation has no was of ensuring that the actual server implementation matches the generated stub (at least without full symbols) so it will blindly marshal pointers or call outside of the object's vtable. Proof of Concept: I’ve provided a PoC as a C# project. You need to compile it first. It fakes out the Windows Search Service’s type library to modify the IGatherManagerAdmin2::GetBackoffReason method so that instead of marshaling a pointer to an integer for returning the caller can specify an arbitrary pointer value. When the method on the server side completes it will try and write a value to this address which will cause a Write AV. The Windows Search service would be ideal for abuse but many of the functions seem to require Administrator access to call. That’s not to say you couldn’t convert this into a full working exploit but I didn’t. 1) Compile the C# project. It should be compiled as a 64 bit executable. 2) Restart the Windows Search service just to ensure it hasn’t cached the stub previously. This probably isn’t necessary but just to be certain. 3) Attach a debugger to SearchIndexer.exe to catch the crash. 4) Execute the PoC as a normal user (do not run under the VSHOST as the CoInitializeSecurity call will fail). You need to pass the path to the provided mssitlb.tlb file which has been modified appropriately. 5) The service should crash trying to write a value to address 0x12345678 Crash Dump: 0:234> r rax=0000015ee04665a0 rbx=0000015ee0466658 rcx=0000015ee0466658 rdx=0000000000000000 rsi=0000000000000004 rdi=0000000000000000 rip=00007fff80e3a75d rsp=00000036541fdae0 rbp=00000036541fdb20 r8=00000036541fd868 r9=0000015ee3bb50b0 r10=0000000000000000 r11=0000000000000246 r12=0000015ee3c02988 r13=00000036541fe1c0 r14=0000000012345678 r15=0000000000000000 iopl=0 nv up ei pl zr na po nc cs=0033 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 MSSRCH!CGatheringManager::GetBackoffReason+0x8d: 00007fff`80e3a75d 418936 mov dword ptr [r14],esi ds:00000000`12345678=???????? 0:234> k # Child-SP RetAddr Call Site 00 00000036`541fdae0 00007fff`b416d533 MSSRCH!CGatheringManager::GetBackoffReason+0x8d 01 00000036`541fdb10 00007fff`b413b0d0 RPCRT4!Invoke+0x73 02 00000036`541fdb60 00007fff`b2fa479a RPCRT4!NdrStubCall2+0x430 03 00000036`541fe180 00007fff`b3853c93 combase!CStdStubBuffer_Invoke+0x9a [d:\th\com\combase\ndr\ndrole\stub.cxx @ 1446] 04 00000036`541fe1c0 00007fff`b305ccf2 OLEAUT32!CUnivStubWrapper::Invoke+0x53 05 (Inline Function) --------`-------- combase!InvokeStubWithExceptionPolicyAndTracing::__l7::<lambda_b8ffcec6d47a5635f374132234a8dd15>::operator()+0x42 [d:\th\com\combase\dcomrem\channelb.cxx @ 1805] 06 00000036`541fe210 00007fff`b3001885 combase!ObjectMethodExceptionHandlingAction<<lambda_b8ffcec6d47a5635f374132234a8dd15> >+0x72 [d:\th\com\combase\dcomrem\excepn.hxx @ 91] 07 (Inline Function) --------`-------- combase!InvokeStubWithExceptionPolicyAndTracing+0x9e [d:\th\com\combase\dcomrem\channelb.cxx @ 1808] 08 00000036`541fe280 00007fff`b3006194 combase!DefaultStubInvoke+0x275 [d:\th\com\combase\dcomrem\channelb.cxx @ 1880] 09 (Inline Function) --------`-------- combase!SyncStubCall::Invoke+0x1b [d:\th\com\combase\dcomrem\channelb.cxx @ 1934] 0a (Inline Function) --------`-------- combase!SyncServerCall::StubInvoke+0x1b [d:\th\com\combase\dcomrem\servercall.hpp @ 736] 0b (Inline Function) --------`-------- combase!StubInvoke+0x297 [d:\th\com\combase\dcomrem\channelb.cxx @ 2154] 0c 00000036`541fe4a0 00007fff`b3008b47 combase!ServerCall::ContextInvoke+0x464 [d:\th\com\combase\dcomrem\ctxchnl.cxx @ 1568] 0d (Inline Function) --------`-------- combase!CServerChannel::ContextInvoke+0x83 [d:\th\com\combase\dcomrem\ctxchnl.cxx @ 1458] 0e (Inline Function) --------`-------- combase!DefaultInvokeInApartment+0x9e [d:\th\com\combase\dcomrem\callctrl.cxx @ 3438] 0f 00000036`541fe770 00007fff`b3007ccd combase!AppInvoke+0x8a7 [d:\th\com\combase\dcomrem\channelb.cxx @ 1618] 10 00000036`541fe8a0 00007fff`b300b654 combase!ComInvokeWithLockAndIPID+0xb2d [d:\th\com\combase\dcomrem\channelb.cxx @ 2686] 11 00000036`541feb30 00007fff`b40fd433 combase!ThreadInvoke+0x1724 [d:\th\com\combase\dcomrem\channelb.cxx @ 6954] 12 00000036`541fedc0 00007fff`b40fbed8 RPCRT4!DispatchToStubInCNoAvrf+0x33 13 00000036`541fee10 00007fff`b40fcf04 RPCRT4!RPC_INTERFACE::DispatchToStubWorker+0x288 14 00000036`541fef10 00007fff`b40f922d RPCRT4!RPC_INTERFACE::DispatchToStubWithObject+0x404 15 00000036`541fefb0 00007fff`b40f9da9 RPCRT4!LRPC_SCALL::DispatchRequest+0x35d 16 00000036`541ff090 00007fff`b40f64dc RPCRT4!LRPC_SCALL::HandleRequest+0x829 17 00000036`541ff180 00007fff`b40f48c9 RPCRT4!LRPC_SASSOCIATION::HandleRequest+0x45c 18 00000036`541ff200 00007fff`b411eaca RPCRT4!LRPC_ADDRESS::ProcessIO+0xb29 19 00000036`541ff350 00007fff`b422e490 RPCRT4!LrpcIoComplete+0x10a 1a 00000036`541ff3f0 00007fff`b422bc66 ntdll!TppAlpcpExecuteCallback+0x360 1b 00000036`541ff4a0 00007fff`b34b8102 ntdll!TppWorkerThread+0x916 1c 00000036`541ff8b0 00007fff`b425c5b4 KERNEL32!BaseThreadInitThunk+0x22 1d 00000036`541ff8e0 00000000`00000000 ntdll!RtlUserThreadStart+0x34 Expected Result: Not doing what ever it did. Observed Result: It did it! Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/42021.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_7 >> Version *

Microsoft>>Windows_8.1 >> Version *

Microsoft>>Windows_rt_8.1 >> Version *

Microsoft>>Windows_server_2008 >> Version *

Microsoft>>Windows_server_2008 >> Version r2

Microsoft>>Windows_server_2012 >> Version -

Microsoft>>Windows_server_2012 >> Version r2

Microsoft>>Windows_server_2016 >> Version *

References

https://www.exploit-db.com/exploits/42021/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securityfocus.com/bid/98103
Tags : vdb-entry, x_refsource_BID

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