CVE-2019-1150 : Detail

CVE-2019-1150

8.8
/
High
OverflowCode Injection
A03-Injection
26.89%V3
Network
2019-08-14
18h55 +00:00
2024-06-04
17h12 +00:00
CVE.org
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CVE Descriptions

Microsoft Graphics Remote Code Execution Vulnerability

A remote code execution vulnerability exists when the Windows font library improperly handles specially crafted embedded fonts. An attacker who successfully exploited the vulnerability could take control of the affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. There are multiple ways an attacker could exploit the vulnerability: In a web-based attack scenario, an attacker could host a specially crafted website that is designed to exploit the vulnerability and then convince users to view the website. An attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by getting them to click a link in an email or instant message that takes users to the attacker's website, or by opening an attachment sent through email. In a file-sharing attack scenario, an attacker could provide a specially crafted document file designed to exploit the vulnerability and then convince users to open the document file. The security update addresses the vulnerability by correcting how the Windows font library handles embedded fonts.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-787 Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
CWE-94 Improper Control of Generation of Code ('Code Injection')
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

Metrics

Metrics Score Severity CVSS Vector Source
V3.1 8.8 HIGH CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C

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.

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 a 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 in the description of a vulnerability.

Exploit Code Maturity

This metric measures the likelihood of the vulnerability being attacked, and is typically based on the current state of exploit techniques, exploit code availability, or active, “in-the-wild” exploitation.

Proof-of-Concept

Proof-of-concept exploit code is available, or an attack demonstration is not practical for most systems. The code or technique is not functional in all situations and may require substantial modification by a skilled attacker.

Remediation Level

The Remediation Level of a vulnerability is an important factor for prioritization.

Official fix

A complete vendor solution is available. Either the vendor has issued an official patch, or an upgrade is available.

Report Confidence

This metric measures the degree of confidence in the existence of the vulnerability and the credibility of the known technical details.

Confirmed

Detailed reports exist, or functional reproduction is possible (functional exploits may provide this). Source code is available to independently verify the assertions of the research, or the author or vendor of the affected code has confirmed the presence of the 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.
V3.1 8.8 HIGH CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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.

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.

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 a 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 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.

 secure@microsoft.com
V2 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C nvd@nist.gov

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 : 47265

Publication date : 2019-08-14 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

-----=====[ Background ]=====----- The Microsoft Font Subsetting DLL (fontsub.dll) is a default Windows helper library for subsetting TTF fonts; i.e. converting fonts to their more compact versions based on the specific glyphs used in the document where the fonts are embedded. It is used by Windows GDI and Direct2D, and parts of the same code are also found in the t2embed.dll library designed to load and process embedded fonts. The DLL exposes two API functions: CreateFontPackage and MergeFontPackage. We have developed a testing harness which invokes a pseudo-random sequence of such calls with a chosen font file passed as input. This report describes a crash triggered by a malformed font file in the fontsub.dll code through our harness. -----=====[ Description ]=====----- We have encountered crashes in fontsub!ReadTableIntoStructure similar to the following: --- cut --- (7ac.378c): Access violation - code c0000005 (first chance) First chance exceptions are reported before any exception handling. This exception may be expected and handled. FONTSUB!ReadTableIntoStructure+0x378: 00007fff`c0874150 6689540110 mov word ptr [rcx+rax+10h],dx ds:000001f7`a7429010=???? 0:000> ? rcx Evaluate expression: 32 = 00000000`00000020 0:000> ? rax Evaluate expression: 2163174707168 = 000001f7`a7428fe0 0:000> ? dx Evaluate expression: 3 = 00000000`00000003 0:000> !heap -p -a rax address 000001f7a7428fe0 found in _DPH_HEAP_ROOT @ 1f7a7271000 in busy allocation ( DPH_HEAP_BLOCK: UserAddr UserSize - VirtAddr VirtSize) 1f7a7276c98: 1f7a7428fe0 20 - 1f7a7428000 2000 00007fffcf6530df ntdll!RtlDebugAllocateHeap+0x000000000000003f 00007fffcf60b52c ntdll!RtlpAllocateHeap+0x0000000000077d7c 00007fffcf59143b ntdll!RtlpAllocateHeapInternal+0x00000000000005cb 00007fff9b90be42 vrfcore!VfCoreRtlAllocateHeap+0x0000000000000022 00007fffcca398f0 msvcrt!malloc+0x0000000000000070 00007fffc086fd1e FONTSUB!Mem_Alloc+0x0000000000000012 00007fffc0875562 FONTSUB!MergeEblcEbdtTables+0x0000000000000b02 00007fffc086b0a3 FONTSUB!MergeFonts+0x0000000000000603 00007fffc086baac FONTSUB!MergeDeltaTTF+0x00000000000003ec 00007fffc08614b2 FONTSUB!MergeFontPackage+0x0000000000000132 [...] 0:000> k # Child-SP RetAddr Call Site 00 000000d8`664fd3d0 00007fff`c0875599 FONTSUB!ReadTableIntoStructure+0x378 01 000000d8`664fd480 00007fff`c086b0a3 FONTSUB!MergeEblcEbdtTables+0xb39 02 000000d8`664fd690 00007fff`c086baac FONTSUB!MergeFonts+0x603 03 000000d8`664fd840 00007fff`c08614b2 FONTSUB!MergeDeltaTTF+0x3ec 04 000000d8`664fd980 00007ff6`1a8a8a30 FONTSUB!MergeFontPackage+0x132 [...] --- cut --- In total, we have discovered crashes in four different locations inside the ReadTableIntoStructure() function. The issue reproduces on a fully updated Windows 10 1709; we haven't tested earlier versions of the system. It could be potentially used to execute arbitrary code in the context of the FontSub client process. It is easiest to reproduce with PageHeap enabled, but it is also possible to observe a crash in a default system configuration. Attached are 4 proof of concept malformed font files which trigger the crash. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/47265.zip
Exploit Database EDB-ID : 47267

Publication date : 2019-08-14 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

-----=====[ Background ]=====----- The Microsoft Font Subsetting DLL (fontsub.dll) is a default Windows helper library for subsetting TTF fonts; i.e. converting fonts to their more compact versions based on the specific glyphs used in the document where the fonts are embedded. It is used by Windows GDI and Direct2D, and parts of the same code are also found in the t2embed.dll library designed to load and process embedded fonts. The DLL exposes two API functions: CreateFontPackage and MergeFontPackage. We have developed a testing harness which invokes a pseudo-random sequence of such calls with a chosen font file passed as input. This report describes a crash triggered by a malformed font file in the fontsub.dll code through our harness. -----=====[ Description ]=====----- We have encountered the following crash in fontsub!WriteTableFromStructure: --- cut --- (3890.25ac): Access violation - code c0000005 (first chance) First chance exceptions are reported before any exception handling. This exception may be expected and handled. FONTSUB!WriteTableFromStructure+0x6e: 00007fff`aa544326 0fb74810 movzx ecx,word ptr [rax+10h] ds:000001ac`2d48a000=???? 0:000> dd rax 000001ac`2d489ff0 d0d0d0c0 d0d0d0d0 d0d0d0d0 d0d0d0d0 000001ac`2d48a000 ???????? ???????? ???????? ???????? 000001ac`2d48a010 ???????? ???????? ???????? ???????? 000001ac`2d48a020 ???????? ???????? ???????? ???????? 000001ac`2d48a030 ???????? ???????? ???????? ???????? 000001ac`2d48a040 ???????? ???????? ???????? ???????? 000001ac`2d48a050 ???????? ???????? ???????? ???????? 000001ac`2d48a060 ???????? ???????? ???????? ???????? 0:000> !heap -p -a rax address 000001ac2d489ff0 found in _DPH_HEAP_ROOT @ 1ac2d041000 in busy allocation ( DPH_HEAP_BLOCK: UserAddr UserSize - VirtAddr VirtSize) 1ac2d0495b0: 1ac2d489ff0 1 - 1ac2d489000 2000 00007fffcf6530df ntdll!RtlDebugAllocateHeap+0x000000000000003f 00007fffcf60b52c ntdll!RtlpAllocateHeap+0x0000000000077d7c 00007fffcf59143b ntdll!RtlpAllocateHeapInternal+0x00000000000005cb 00007fff9b90be42 vrfcore!VfCoreRtlAllocateHeap+0x0000000000000022 00007fffcca398f0 msvcrt!malloc+0x0000000000000070 00007fffaa53fd1e FONTSUB!Mem_Alloc+0x0000000000000012 00007fffaa545562 FONTSUB!MergeEblcEbdtTables+0x0000000000000b02 00007fffaa53b0a3 FONTSUB!MergeFonts+0x0000000000000603 00007fffaa53baac FONTSUB!MergeDeltaTTF+0x00000000000003ec 00007fffaa5314b2 FONTSUB!MergeFontPackage+0x0000000000000132 [...] 0:000> k # Child-SP RetAddr Call Site 00 00000078`dc2fd380 00007fff`aa545634 FONTSUB!WriteTableFromStructure+0x6e 01 00000078`dc2fd490 00007fff`aa53b0a3 FONTSUB!MergeEblcEbdtTables+0xbd4 02 00000078`dc2fd6a0 00007fff`aa53baac FONTSUB!MergeFonts+0x603 03 00000078`dc2fd850 00007fff`aa5314b2 FONTSUB!MergeDeltaTTF+0x3ec 04 00000078`dc2fd990 00007ff6`1a8a8a30 FONTSUB!MergeFontPackage+0x132 [...] --- cut --- The root cause of the crash seems to be the fact that the MergeEblcEbdtTables() function may allocate a 0-sized buffer and pass it to WriteTableFromStructure() as one of the fields of a structure passed through the fifth argument, but the WriteTableFromStructure() function assumes that the buffer is at least 32 bytes long, and unconditionally reads from it at offset 16, and other offsets later on in the routine. The issue reproduces on a fully updated Windows 10 1709; we haven't tested earlier 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 3 proof of concept malformed font files which trigger the crash. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/47267.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_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