MS-ISAC CYBERSECURITY ADVISORIES

MS-ISAC ADVISORY NUMBER:
2017-015

DATE(S) ISSUED:
02/27/2017

SUBJECT:
Vulnerability in Microsoft Internet Explorer and Edge Could Allow for Arbitrary Code Execution

OVERVIEW:

A vulnerability has been discovered in Microsoft Internet Explorer and Microsoft Edge, which could allow arbitrary code execution if a user views a specially crafted web page. Microsoft Edge replaced Internet Explorer as the default browser on Windows 10. Successful exploitation of this vulnerability could result in an attacker executing arbitrary code in the context of the logged on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.

THREAT INTELLIGENCE:

This vulnerability has been publicly disclosed. There are no reports of this vulnerability being exploited in the wild.

SYSTEMS AFFECTED:

·Microsoft Edge

·Microsoft Internet Explorer 10

·Microsoft Internet Explorer 11

 

RISK:

Government:

·Large and medium government entities:High

·Small government:High

Businesses:

·Large and medium business entities:High

·Small business entities:High

Home users: High

TECHNICAL SUMMARY:

A vulnerability has been discovered in Microsoft Edge, which could allow for remote code execution if a user views a specially crafted web page. Microsoft Internet Explorer and Edge are prone to a remote memory-corruption vulnerability due to a type confusion error. Specifically, this issue affects the 'Layout::MultiColumnBoxBuilder::HandleColumnBreakOnColumnSpanningElement' function in the 'mshtml.dll'. An attacker can exploit this issue through a specially crafted Cascading Style Sheets (CSS) token sequence and JavaScript code that operates on a TH element. Attackers can exploit this issue to execute arbitrary code in the context of the currently logged-in user. Failed attacks will cause denial of service conditions.

RECOMMENDATIONS:

We recommend the following actions be taken:

· Run all software as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack.

· Consider using an alternative browser until a patch is available. Once the patch provided by Microsoft is available, apply it to vulnerable systems immediately after appropriate testing.

· Remind users not to visit un-trusted websites or follow links provided by unknown or un-trusted sources.

· Inform and educate users regarding the threats posed by hypertext links contained in emails or attachments, especially those from un-trusted sources.

· Apply the Principle of Least Privilege to all systems and services.

REFERENCES:
Microsoft:
https://bugs.chromium.org/p/project-zero/issues/detail?id=1011

CVE:
http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-0037