CVE-2019-1245 : Detail

CVE-2019-1245

6.5
/
Medium
A01-Broken Access Control
4.91%V3
Network
2019-09-11
19h24 +00:00
2019-09-11
19h24 +00:00
CVE.org
NVD
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CVE Descriptions

An information disclosure vulnerability exists when DirectWrite improperly discloses the contents of its memory, aka 'DirectWrite Information Disclosure Vulnerability'. This CVE ID is unique from CVE-2019-1244, CVE-2019-1251.

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
V3.1 6.5 MEDIUM CVSS:3.1/AV:N/AC:L/PR:N/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.

Network

The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).

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 when attacking the vulnerable component.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

None

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

User Interaction

This metric captures the requirement for a human 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

The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope.

Scope

Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs.

Unchanged

An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.

Base: Impact Metrics

The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve.

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 a 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 in the description of a vulnerability.

Environmental Metrics

These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.

 [email protected]
V2 4.3 AV:N/AC:M/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 : 47381

Publication date : 2019-09-11 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Microsoft DirectWrite is a modern Windows API for high-quality text rendering. A majority of its code resides in the DWrite.dll user-mode library. It is used by a variety of widely used desktop programs (such as the Chrome, Firefox and Edge browsers) and constitutes an attack surface for memory corruption bugs, as it performs the processing of untrusted font files and is written in C/C++. Through fuzzing, we have discovered a crash caused by an invalid memory read in DWrite!SplicePixel, while rasterizing the glyphs of a slightly malformed OpenType font. The problem reproduces in all major browsers; below is a crash log from the Microsoft Edge renderer process, generated when trying to open a web page with the proof-of-concept font embedded: --- cut --- (281c.25d4): Access violation - code c0000005 (first chance) First chance exceptions are reported before any exception handling. This exception may be expected and handled. DWrite!SplicePixel+0x14b: 00007fff`b8634473 488b14f0 mov rdx,qword ptr [rax+rsi*8] ds:00000227`c62d95b0=???????????????? 0:031> u DWrite!SplicePixel+0x14b: 00007fff`b8634473 488b14f0 mov rdx,qword ptr [rax+rsi*8] 00007fff`b8634477 4885d2 test rdx,rdx 00007fff`b863447a 7474 je DWrite!SplicePixel+0x1c8 (00007fff`b86344f0) 00007fff`b863447c 458d4b01 lea r9d,[r11+1] 00007fff`b8634480 8b4208 mov eax,dword ptr [rdx+8] 00007fff`b8634483 413bc1 cmp eax,r9d 00007fff`b8634486 7f68 jg DWrite!SplicePixel+0x1c8 (00007fff`b86344f0) 00007fff`b8634488 488b0a mov rcx,qword ptr [rdx] 0:031> ? rax Evaluate expression: 2369851854688 = 00000227`c62d8f60 0:031> ? rsi Evaluate expression: 202 = 00000000`000000ca 0:031> dd rax 00000227`c62d8f60 ???????? ???????? ???????? ???????? 00000227`c62d8f70 ???????? ???????? ???????? ???????? 00000227`c62d8f80 ???????? ???????? ???????? ???????? 00000227`c62d8f90 ???????? ???????? ???????? ???????? 00000227`c62d8fa0 ???????? ???????? ???????? ???????? 00000227`c62d8fb0 ???????? ???????? ???????? ???????? 00000227`c62d8fc0 ???????? ???????? ???????? ???????? 00000227`c62d8fd0 ???????? ???????? ???????? ???????? 0:031> k # Child-SP RetAddr Call Site 00 000000b4`ceaebe00 00007fff`b8634306 DWrite!SplicePixel+0x14b 01 000000b4`ceaebe50 00007fff`b8633325 DWrite!SetPixelInDropOut+0x9a 02 000000b4`ceaebe90 00007fff`b86322a8 DWrite!FillInInflection+0xcd 03 000000b4`ceaebf00 00007fff`b863281b DWrite!DoXInflections+0x118 04 000000b4`ceaebf40 00007fff`b86319ca DWrite!EditBlackSpace+0x29f 05 000000b4`ceaebfa0 00007fff`b8636118 DWrite!CScan+0x72 06 000000b4`ceaebff0 00007fff`b855b1b2 DWrite!CScanFill+0x204 07 000000b4`ceaec0e0 00007fff`b848ccef DWrite!DoType1InterpretCharString+0xcd77a 08 000000b4`ceaec790 00007fff`b862ea16 DWrite!Type1InterpretCharString+0x163 09 000000b4`ceaec880 00007fff`b862dd49 DWrite!BuildRuns+0x186 0a 000000b4`ceaec9b0 00007fff`b862b2b9 DWrite!ATMBuildBitMap+0xb9 0b 000000b4`ceaeca80 00007fff`b85b88b7 DWrite!AdobeInternalGetBitmap+0x31d 0c 000000b4`ceaecd20 00007fff`b85b877a DWrite!CffRasterizer::Implementation::GetBitmap+0x11f 0d 000000b4`ceaece60 00007fff`b84e2c89 DWrite!CffRasterizer::GetBitmap+0x2a 0e 000000b4`ceaecea0 00007fff`b84b1754 DWrite!GlyphBitmapRasterizationState::RasterizeGlyph+0x111 0f 000000b4`ceaecee0 00007fff`c8e3e1ce DWrite!DWriteGlyphLookupCache::GetGlyphBitmapInfo+0x264 10 000000b4`ceaed150 00007fff`c8e3e95f d2d1!GlyphRunAnalyzer::AddCachedGlyph+0x62 11 000000b4`ceaed200 00007fff`c8e460b0 d2d1!GlyphRunAnalyzer::GetGlyphs+0x18f 12 000000b4`ceaed250 00007fff`c8e5572d d2d1!GlyphRunRenderer::InitForRendering+0x2c0 13 000000b4`ceaed390 00007fff`c8ebffe4 d2d1!CHwSurfaceRenderTarget::DrawGlyphRun+0x38d 14 000000b4`ceaed6a0 00007fff`c8e5379e d2d1!BrushRedirectionCompatibleCommand<CCommand_DrawGlyphRun,0>::Execute+0x134 15 000000b4`ceaed7b0 00007fff`c8e6e7ef d2d1!CHwSurfaceRenderTarget::ProcessBatch+0x3ce 16 000000b4`ceaed860 00007fff`c8e6a0ae d2d1!CBatchSerializer::FlushInternal+0x13f 17 000000b4`ceaed8f0 00007fff`c8e6143b d2d1!DrawingContext::Flush+0x96 18 000000b4`ceaed950 00007fff`9dba551e d2d1!D2DDeviceContextBase<ID2D1DeviceContext6,ID2D1DeviceContext6,null_type>::EndDraw+0x13b 19 000000b4`ceaeda90 00007fff`9da3a704 edgehtml!CDXRenderTarget::EndDrawD2D+0x66 1a 000000b4`ceaedac0 00007fff`9da3a4e8 edgehtml!CDXRenderTarget::EnsureRenderMode+0x184 1b 000000b4`ceaedaf0 00007fff`9db9db85 edgehtml!CDXRenderTarget::EndDraw+0x38 1c 000000b4`ceaedb40 00007fff`9db9da0b edgehtml!CDispSurface::EndLayerToRenderTarget+0x145 1d 000000b4`ceaedbe0 00007fff`9da2585f edgehtml!CDispNodeDestination::EndRender+0x6b 1e 000000b4`ceaedc50 00007fff`9db660c1 edgehtml!CDispNodeDestination::EndRect+0xaf 1f 000000b4`ceaedc90 00007fff`9da1cf83 edgehtml!CDispDestinationDrawHelper::EndRect+0x31 20 000000b4`ceaedcc0 00007fff`9d9de055 edgehtml!CDispContainer::DrawSelfContent+0x583 21 000000b4`ceaede30 00007fff`9d9df37e edgehtml!CDispContainer::DrawSelf+0x365 22 000000b4`ceaedfc0 00007fff`9da1ee43 edgehtml!CDispNode::DrawInternal+0x7ce 23 000000b4`ceaee350 00007fff`9da1d747 edgehtml!CDispNode::Draw+0x943 24 000000b4`ceaee560 00007fff`9da1d297 edgehtml!CDispContainer::DrawChildren+0x227 25 000000b4`ceaee620 00007fff`9da1cbc8 edgehtml!CDispContainer::DrawSelfContentFullStackingContext+0x127 26 000000b4`ceaee710 00007fff`9d9de055 edgehtml!CDispContainer::DrawSelfContent+0x1c8 27 000000b4`ceaee880 00007fff`9d9df37e edgehtml!CDispContainer::DrawSelf+0x365 28 000000b4`ceaeea10 00007fff`9da1ead3 edgehtml!CDispNode::DrawInternal+0x7ce 29 000000b4`ceaeeda0 00007fff`9da2a8fc edgehtml!CDispNode::Draw+0x5d3 2a 000000b4`ceaeefb0 00007fff`9da29b68 edgehtml!CDispRoot::DrawIndependentCompositionLayerTree+0x5c 2b 000000b4`ceaef0a0 00007fff`9da297f5 edgehtml!CDispRoot::DrawRoot+0x1b8 2c 000000b4`ceaef2f0 00007fff`9daa452c edgehtml!CPaintHandler::RenderInternal+0x2b5 2d 000000b4`ceaef870 00007fff`9d9c4ac8 edgehtml!CPaintHandler::RenderIfNeeded+0x7c 2e 000000b4`ceaef8e0 00007fff`9dbaa80d edgehtml!CRenderThread::ProcessRenderWork+0xdc 2f 000000b4`ceaef940 00007fff`9dacfdb9 edgehtml!CRenderTaskDrawInPlace::Execute+0xad 30 000000b4`ceaef9b0 00007fff`9dbe7542 edgehtml!CRenderThread::RenderThread+0x229 31 000000b4`ceaefa50 00007fff`cec537e4 edgehtml!CRenderThread::StaticRenderThreadProc+0x42 32 000000b4`ceaefa80 00007fff`cf5bcb81 KERNEL32!BaseThreadInitThunk+0x14 33 000000b4`ceaefab0 00000000`00000000 ntdll!RtlUserThreadStart+0x21 --- cut --- We have minimized the test case to a single-byte difference in relation to the original file. When decompiled with the "ttx" utility from the fontTools package, the difference becomes obvious: it's a change of one of the FontMatrix values inside the CFF table. Original data: <FontMatrix value="0.001 0.0 0.000123 0.001 0.0 0.0"/> Mutated data: <FontMatrix value="0.001 2000000.0 0.000123 0.001 0.0 0.0"/> The issue reproduces on a fully updated Windows 7 and Windows 10 1709; we haven't tested other versions of the system. It could be potentially used to disclose sensitive data from the process address space. It is easiest to reproduce with PageHeap enabled, but it is also possible to observe a crash in a default system configuration. Attached are the minimized PoC font, original font, an HTML file to reproduce the bug in a browser, and 3 extra non-minimized samples which also trigger the crash. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/47381.zip

Products Mentioned

Configuraton 0

Microsoft>>Windows_10 >> Version -

Microsoft>>Windows_10 >> Version 1607

Microsoft>>Windows_10 >> Version 1703

Microsoft>>Windows_10 >> Version 1709

Microsoft>>Windows_10 >> Version 1803

Microsoft>>Windows_10 >> Version 1809

Microsoft>>Windows_10 >> Version 1903

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_2008 >> Version r2

Microsoft>>Windows_server_2012 >> Version -

Microsoft>>Windows_server_2012 >> Version r2

Microsoft>>Windows_server_2016 >> Version -

Microsoft>>Windows_server_2016 >> Version 1803

Microsoft>>Windows_server_2016 >> Version 1903

Microsoft>>Windows_server_2019 >> Version -

References