Microsoft Internet Explorer 8/9/10/11 Regex vbscript.dll RegExpComp::PnodeParse memory corruption

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.8	$5k-$25k	0.00

A vulnerability was found in Microsoft Internet Explorer 8/9/10/11 (Web Browser). It has been declared as critical. Affected by this vulnerability is the function RegExpComp::PnodeParse in the library vbscript.dll of the component Regex Handler. The manipulation with an unknown input leads to a memory corruption vulnerability. The CWE definition for the vulnerability is CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. As an impact it is known to affect confidentiality, integrity, and availability.

The weakness was published 11/08/2016 by Berend-Jan Wever (SkyLined) as VBScript RegExpComp::PnodeParse out-of-bounds read details (MSIE 8-11, IIS, CScript.exe/WScript.exe) as not defined mailinglist post (Full-Disclosure). It is possible to read the advisory at seclists.org. The vendor was not involved in the public release. The mailinglist post contains:

May 2015: ZDI rejects the submission.

The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 04/07/2017). It is expected to see the exploit prices for this product decreasing in the near future. The advisory points out:

When a regular expression is used to find matches in a string, it is first "compiled". During compilation, when a '\' escape character is encountered, the RegExpComp::PnodeParse function reads the next character to determine the type of escape sequence. However, if the last character in a regular expression is a '\' character, the code will read and use the terminating '\0' character as the second character in the escape sequence. This causes the code to ignore the end of the string and continue to compile whatever data is found beyond it as if it was part of the regular expression.

The real existence of this vulnerability is still doubted at the moment.

Upgrading to version 11 eliminates this vulnerability. The mailinglist post contains the following remark:

November 2016: The issue does not reproduce in the latest build of MSIE 11.

Productinfo

Type

Web Browser

Vendor

Microsoft

Name

Internet Explorer

Version

License

commercial

Support

end of life

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB CVSS-B Score: 🔍
VulDB CVSS-BT Score: 🔍
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 5.8

VulDB Base Score: 6.3
VulDB Temp Score: 5.8
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
unlock	unlock	unlock	unlock	unlock	unlock
unlock	unlock	unlock	unlock	unlock	unlock
unlock	unlock	unlock	unlock	unlock	unlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Memory corruption
CWE: CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	unlock	unlock	unlock	unlock
Today	unlock	unlock	unlock	unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Internet Explorer 11

Timelineinfo

11/08/2016 🔍
11/10/2016 +2 days 🔍
04/07/2017 +148 days 🔍

Sourcesinfo

Vendor: microsoft.com

Advisory: VBScript RegExpComp::PnodeParse out-of-bounds read details (MSIE 8-11, IIS, CScript.exe/WScript.exe)
Researcher: Berend-Jan Wever (SkyLined)
Status: Not defined
Disputed: 🔍

Entryinfo

Created: 11/10/2016 08:09
Updated: 04/07/2017 12:15
Changes: 11/10/2016 08:09 (53), 04/07/2017 12:15 (2)
Complete: 🔍