CVE-2016-0170 : Detail

CVE-2016-0170

8.8
/
High
A01-Broken Access Control
41.36%V3
Network
2016-05-10
23h00 +00:00
2018-10-12
17h57 +00:00
CVE.org
NVD
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CVE Descriptions

GDI in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, and Windows 10 Gold and 1511 allows remote attackers to execute arbitrary code via a crafted document, aka "Windows Graphics Component RCE Vulnerability."

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-284 Improper Access Control
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 8.8 HIGH CVSS:3.0/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

A vulnerability exploitable with network access means the vulnerable component is bound to the network stack and the attacker's path is through OSI layer 3 (the network layer). Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable one or more network hops away (e.g. across layer 3 boundaries from 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 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

 [email protected]
V2 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C [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 : 39834

Publication date : 2016-05-16 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=731 Two of the escape codes supported by the public ExtEscape() API are POSTSCRIPT_IDENTIFY and POSTSCRIPT_INJECTION, which are only processed if the Device Context is associated with a printer. In the code responsible for handling the two escape codes, we can find the following constructs: --- cut --- .text:7DAE3E9F mov ecx, [ebp+cjInput] .text:7DAE3EA2 lea eax, [ecx+1Ah] .text:7DAE3EA5 add ecx, 17h .text:7DAE3EA8 cmp eax, ecx .text:7DAE3EAA jb loc_7DAD19AD .text:7DAE3EB0 and eax, 0FFFFFFFCh .text:7DAE3EB3 mov [ebp+Size], eax .text:7DAE3EB9 push [ebp+Size] ; Size .text:7DAE3EBF mov eax, large fs:18h .text:7DAE3EC5 mov eax, [eax+30h] .text:7DAE3EC8 push 0 ; Flags .text:7DAE3ECA push dword ptr [eax+18h] ; HeapHandle .text:7DAE3ECD call ds:__imp__RtlAllocateHeap@12 ; RtlAllocateHeap(x,x,x) ... .text:7DAE3EEF mov eax, [ebp+cjInput] .text:7DAE3EF2 push eax ; Size .text:7DAE3EF3 mov [esi+10h], eax .text:7DAE3EF6 lea eax, [esi+14h] .text:7DAE3EF9 push edi ; Src .text:7DAE3EFA push eax ; Dst .text:7DAE3EFB call _memcpy --- cut --- which can be translated to the following C-like pseudocode (assuming 32-bit wide types): --- cut --- if (cjInput + 26 > cjInput > 23) { buffer = Allocate((cjInput + 26) & ~4); ... memcpy(buffer + 20, lpInData, cjInput); ... } --- cut --- From the code snippet shown above, it is clear that while it checks for a possible integer overflow between cjInput+23 and cjInput+26, it does not check if the "+23" part overflows the 32-bit type or not. As a consequence, if cjInput is set to anywhere between -23 and -1, a small heap-based buffer will be allocated (<30 bytes) and the function will try to copy ~4GB of data into it, leading to an obvious buffer overflow condition. Under normal circumstances, the problem can only be triggered with an unusually large value of the cjInput parameter, which is unlikely to be used by a programmer. However, EMF (Enhanced Windows Metafile) files can act as remote proxy for DrawEscape() (via EMR_DRAWESCAPE) and ExtEscape() (via EMR_EXTESCAPE) calls. Interestingly, the corresponding MRESCAPE::bCheckRecord() record verification routine doesn't ensure that the cjInput value is valid (i.e. that enough input data is actually present in the record). As a result, a specially crafted EMF file can pass any controlled value as cjInput, thus potentially /lying/ to ExtEscape() about the number of input bytes. Lack of cjInput sanitization in MRESCAPE::bCheckRecord() is therefore believed to be the culprit of the bug (regardless of the integer overflow in ExtEscape()). While this is just one example of what an arbitrary cjInput parameter passed to DrawEscape() / ExtEscape() may lead to, we suspect that it could also have other security implications, e.g. if any of the functions trust cjInput and read beyond the record buffer, and then use the data in such a way that it is possible to retrieve it back in the client (like Internet Explorer), then it could be used as a memory disclosure primitive. As previously mentioned, the bug only reproduces when the destination HDC is associated with a printer. After a brief search I haven't found a vector to achieve this using existing Windows client applications supporting the EMF format (such as IE), so I've developed a short dedicated program to demonstrate the problem (poc.cc), which boils down to the following API calls: --- cut --- HDC hdc = CreateDC("WINSPOOL", "Fax", NULL, NULL); HENHMETAFILE hemf = GetEnhMetaFile("poc.emf"); RECT rect = {0, 0, 100, 100}; PlayEnhMetaFile(hdc, hemf, &rect); --- cut --- Upon compiling it and starting with the enclosed poc.emf file in the current working directory, the expected crash is generated in memcpy(): --- cut --- (353c.fa4): Access violation - code c0000005 (first chance) First chance exceptions are reported before any exception handling. This exception may be expected and handled. eax=003300e7 ebx=004ffbe8 ecx=3ffffc39 edx=00000003 esi=00331000 edi=00500c1c eip=779823a3 esp=0028fb34 ebp=0028fb3c iopl=0 nv up ei pl nz na po nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010202 ntdll!memcpy+0x33: 779823a3 f3a5 rep movs dword ptr es:[edi],dword ptr [esi] 0:000> kb ChildEBP RetAddr Args to Child 0028fb3c 771a3f00 004ffd04 003300e8 ffffffff ntdll!memcpy+0x33 0028fd98 771c3fa9 bc21881a 00001015 ffffffff GDI32!ExtEscape+0x431 0028fdbc 77194e17 bc21881a 004f9588 00000004 GDI32!MRESCAPE::bPlay+0x32 0028fe34 7719ca93 bc21881a 004f9588 003300d8 GDI32!PlayEnhMetaFileRecord+0x2c5 0028febc 7719caf2 bc21881a 423d5f3a 00000000 GDI32!bInternalPlayEMF+0x66b 0028fed8 00401479 bc21881a b6467a1d 0028fef8 GDI32!PlayEnhMetaFile+0x32 WARNING: Stack unwind information not available. Following frames may be wrong. 0028ff18 004010fd 0028ff28 75949e34 7efde000 image00400000+0x1479 0028ff94 77999882 7efde000 4f2b9f18 00000000 image00400000+0x10fd 0028ffd4 77999855 00401280 7efde000 00000000 ntdll!__RtlUserThreadStart+0x70 0028ffec 00000000 00401280 7efde000 00000000 ntdll!_RtlUserThreadStart+0x1b --- cut --- The bug has been reproduced on a fully patched Windows 7 64-bit with a 32-bit POC program, but the 64-bit build of gdi32.dll also seems to be affected. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/39834.zip

Products Mentioned

Configuraton 0

Microsoft>>Windows_10 >> Version *

Microsoft>>Windows_10 >> Version 1511

Microsoft>>Windows_7 >> Version *

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_vista >> Version *

References

http://www.securitytracker.com/id/1035823
Tags : vdb-entry, x_refsource_SECTRACK
http://www.securityfocus.com/bid/89864
Tags : vdb-entry, x_refsource_BID