CVE-2016-3303 : Detail

CVE-2016-3303

7.8
/
High
A03-Injection
29.78%V3
Local
2016-08-09
19h00 +00:00
2018-10-12
17h57 +00:00
CVE.org
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CVE Descriptions

The Windows font library in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Office 2007 SP3, Office 2010 SP2, Word Viewer, Skype for Business 2016, Lync 2013 SP1, Lync 2010, Lync 2010 Attendee, and Live Meeting 2007 Console allows remote attackers to execute arbitrary code via a crafted embedded font, aka "Windows Graphics Component RCE Vulnerability," a different vulnerability than CVE-2016-3304.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-20 Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 7.8 HIGH CVSS:3.0/AV:L/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.

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.

None

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

User Interaction

This metric captures the requirement for a 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

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.

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 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 that one has in the description of a vulnerability.

Environmental Metrics

 nvd@nist.gov
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 : 40256

Publication date : 2016-08-16 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=826 The GDI+ library can handle bitmaps originating from untrusted sources through a variety of attack vectors, like EMF files, which may embed bitmaps in records such as EMR_PLGBLT, EMR_BITBLT, EMR_STRETCHBLT, EMR_STRETCHDIBITS etc. In a simplified scheme of things, let's introduce the following symbols, as they are calculated by GDI+ (all arithmetic is performed on signed 32-bit types): columns = abs(biHeight) bytes_per_row_signed = biWidth * (((biPlanes * biBitCount + 31) & 0xFFFFFFE0) / 8) While the gdiplus!ValidateBitmapInfo attempts to validate the correctness of the bitmap headers to some degree, it also fills out portions of a structure which is later used to display the bitmap or perform any other operations on the image. One of them is a pointer to the first row of pixels, calculated depending on the signedness of the biHeight field, which indicates if the bitmap is encoded upside-down or not. This is illustrated by the following pseudo-code snippet: --- cut --- if (biHeight > 0) { first_row = &pixels_buffer[bytes_per_row_signed * (biHeight - 1)]; } else { first_row = pixels_buffer; } --- cut --- Even though there are some dependencies between the various fields that must be met, the attacker still has almost full control over the values of both bytes_per_row_signed and biHeight. If the bytes_per_row_signed variable holds a negative value and biHeight is larger than 1, then we can get the first_row pointer to point at a nearly arbitrary location relative to the address of pixels_buffer. The exploitation of this bug is additionally facilitated by a flaw in the gdiplus!GetBitmapFromRecord function, which is supposed to check that the EMF record is sufficiently large to fully contain the bitmap data, and is called at the beginning of the BMP-related EMF record handlers, before any BMP parsing actually takes place. The most interesting expression is as follows: --- cut --- if (record_length - bitmap_data_offset >= GetDibBitsSize(&header)) { return TRUE; } return FALSE; --- cut --- The above check appears to be effective at a first glance, but it turns out that the GetDibBitsSize() function returns 0 if there are any problems detected in the headers, including invalid values in specific fields (biWidth, biHeight, ...), integer overflows etc. As a result, contrary to intuition, a malformed header will cause the above check to automatically pass, opening up the potential for bugs such as the one discussed in this report further in the bitmap handling code. A poc.emf file is attached. It has been confirmed to crash both x86 and x64 builds of a test EMF viewer written in C++, and Microsoft Office 2013. It uses an EMR_PLGBLT record with a malformed, embedded bitmap and the following fields: biWidth = 0x30000000 biHeight = 0x00000002 biPlanes = 0x0001 biBitCount = 0x0008 The above combination of values will lead to GetDibBitsSize() returning 0, bytes_per_row_signed holding a negative value, and the first_row pointer addressing an invalid address lower than the actual buffer: --- cut --- (4144.1e30): Access violation - code c0000005 (first chance) First chance exceptions are reported before any exception handling. This exception may be expected and handled. eax=f046faf4 ebx=0000fdec ecx=00003e72 edx=00000000 esi=f046012c edi=07c7d624 eip=75969b60 esp=0034ec88 ebp=0034ec90 iopl=0 nv up ei pl nz ac pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00210216 msvcrt!memcpy+0x5a: 75969b60 f3a5 rep movs dword ptr es:[edi],dword ptr [esi] 0:000> kb ChildEBP RetAddr Args to Child 0034ec90 6b0a5bd3 07c7d624 f046012c 0000f9c8 msvcrt!memcpy+0x5a 0034ecb0 6b09780d 07c7d1e0 f046012c 20000000 gdiplus!EmfPlusCommentStream::Write+0x9e 0034f584 6b098180 07c7d1e0 00000002 08be4cd8 gdiplus!CopyOnWriteBitmap::GetData+0x3f3 0034f59c 6b0a6029 07c7d1e0 00000002 08be4cd8 gdiplus!GpBitmap::GetData+0x1c 0034f5b4 6b0a8a55 00000005 08be4cd8 00000000 gdiplus!MetafileRecorder::WriteObject+0x49 0034f5d8 6b0a7814 07c7badc 0034f730 07c90d28 gdiplus!MetafileRecorder::RecordObject+0x57 0034f720 6b0a453d 0034f7f8 08be4cd8 00000000 gdiplus!MetafileRecorder::RecordDrawImage+0x93 0034f818 6b0a4838 08be4cd8 00000000 00000000 gdiplus!GpGraphics::DrawImage+0x1f0 0034f87c 6b0c205d 08be4cd8 0034f918 00000003 gdiplus!GpGraphics::DrawImage+0x66 0034f96c 6b0c7ed1 0000004f 07c94cb0 0000a67c gdiplus!CEmfPlusEnumState::PlgBlt+0x264 0034f980 6b0986ca 0000004f 0000a67c 00460074 gdiplus!CEmfPlusEnumState::ProcessRecord+0xe7 0034f99c 6b098862 0000004f 00000000 0000a67c gdiplus!GdipPlayMetafileRecordCallback+0x6c 0034f9c4 773955ec 7021208b 05d56ff8 00460074 gdiplus!EnumEmfDownLevel+0x6e 0034fa50 6b09aa36 7021208b 403581b3 6b0987f4 GDI32!bInternalPlayEMF+0x6a3 0034fa88 6b09d199 7021208b 5e461f1b 0134faf4 gdiplus!MetafilePlayer::EnumerateEmfRecords+0x104 0034fb30 6b09f455 00000000 5e461f1b 0034fc58 gdiplus!GpGraphics::EnumEmf+0x391 0034fc90 6b0a4742 00000000 42901225 42901d0b gdiplus!GpMetafile::EnumerateForPlayback+0x7b9 0034fd8c 6b0a47c6 07c75f28 00000000 00000000 gdiplus!GpGraphics::DrawImage+0x3f5 0034fdf0 6b09c792 07c75f28 0034fe64 0034fe64 gdiplus!GpGraphics::DrawImage+0x51 0034fe28 6b09ea7a 07c75f28 0034fe64 00000005 gdiplus!GpGraphics::DrawMetafileSplit+0x1f 0034fe7c 6b09f4d5 07c71d28 0034ff08 00000000 gdiplus!GpMetafile::ConvertToEmfPlus+0x1c1 0034fea0 6b074f71 07c71d28 0034ff08 00000005 gdiplus!GpMetafile::ConvertToEmfPlus+0x1d 0034fedc 010c117e 07c71d28 07c75f28 0034ff08 gdiplus!GdipConvertToEmfPlus+0xbf ... --- cut --- The above analysis was performed using the gdiplus.dll file found in C:\Windows\winsxs\x86_microsoft.windows.gdiplus_6595b64144ccf1df_1.1.7601.23407_none_5c02a2f5a011f9be\GdiPlus.dll on a fully patched Windows 7 64-bit operating system (md5sum c861ee277cd4e2d914740000161956ef). Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/40256.zip

Products Mentioned

Configuraton 0

Microsoft>>Live_meeting >> Version 2007

Microsoft>>Lync >> Version 2010

Microsoft>>Lync >> Version 2010

Microsoft>>Lync >> Version 2013

Microsoft>>Office >> Version 2007

Microsoft>>Office >> Version 2010

Microsoft>>Skype_for_business >> Version 2016

Microsoft>>Word_viewer >> Version *

Microsoft>>Windows_7 >> Version *

Microsoft>>Windows_server_2008 >> Version *

Microsoft>>Windows_server_2008 >> Version r2

Microsoft>>Windows_vista >> Version *

References

https://www.exploit-db.com/exploits/40256/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securityfocus.com/bid/92301
Tags : vdb-entry, x_refsource_BID
http://www.securitytracker.com/id/1036564
Tags : vdb-entry, x_refsource_SECTRACK