Microsoft Has Pushed Out an Emergency Update to Fix a Critical IE Bug

By Tom Pritchard on at

Do you still use Internet Explorer? Make sure you get it updated pronto, because there's a fairly serious exploit that nasty people are exploiting to install malware onto unsuspecting machines. It's so serious, in fact, that Microsoft has released an emergency patch to fix the problem.

The exploit is currently known by its index code, CVE-2015-2502, and can be exploited if the user visits a malicious website or opens specific HTML-based emails. It works thanks to the way IE stores objects in memory, causing an error that corrupts the memory's contents. It's present in all supported versions of the browser, and just so happens to carry Microsoft's top level of severity.

Microsoft officials said the following in an advisory post yesterday:

A remote code execution vulnerability exists when Internet Explorer improperly accesses objects in memory. This vulnerability could corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user.

An attacker could host a specially crafted website that is designed to exploit this vulnerability through Internet Explorer, and then convince a user to view the website. The attacker could also take advantage of compromised websites and websites that accept or host user-provided content or advertisements by adding specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by getting them to click a link in an instant messenger or email message that takes users to the attacker's website, or by getting them to open an attachment sent through email.

An attacker who successfully exploited this vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.

The post claims that the exploit is being actively exploited, but didn't provide any other details.

It sounds pretty nasty, though, so if you want to make sure nefarious individuals are not screwing around with your computer make sure you get that update in as soon as possible. Or avoid using IE altogether, whatever works best.[Microsoft via Ars Technica]