Four Zero Days Disclosed in Internet Explorer Mobile

IE microchip

UPDATE–As if all of the vulnerabilities in Flash and Windows discovered in the Hacking Team document cache and the 193 bugs Oracle fixed last week weren’t enough for organizations to deal with, HP’s Zero Day Initiative has released four new zero days in Internet Explorer Mobile that can lead to remote code execution on Windows Phones.

The four vulnerabilities originally were reported to Microsoft as affecting IE on the desktop, and later on it was discovered that they also affected IE Mobile on Windows Phones. Microsoft has patched all of the vulnerabilities in the desktop version of the browser, but the bugs remain open on IE Mobile. ZDI’s original advisories on these flaws said that they were zero days on Internet Explorer, as well. The company updated the advisories late Thursday to reflect the fact that the bugs only affect IE Mobile.

“We’re aware of the reports regarding Internet Explorer for Windows Phone. A number of factors would need to come into play, and no attacks have been reported. We continue to monitor the situation and will take appropriate steps to protect our customers,” a Microsoft spokesperson said.

Each of the four vulnerabilities is in a different component of the browser, but they all are remotely exploitable. The advisories from ZDI say that attackers could exploit these vulnerabilities through typical drive-by attacks.

The most severe of the four vulnerabilities is a bug in the way that Internet Explorer handles some specific arrays.

“The vulnerability relates to how Internet Explorer processes arrays representing cells in HTML tables. By manipulating a document’s elements an attacker can force a Internet Explorer to use memory past the end of an array of HTML cells. An attacker can leverage this vulnerability to execute code under the context of the current process,” the advisory from ZDI says.

That vulnerability was discovered as part of the Mobile Pwn2Own contest in November and ZDI disclosed it to Microsoft at the time. ZDI has a policy of disclosing privately reported vulnerabilities after 120 days, even if the affected vendor has not released a patch. Microsoft has not issued patches for any of the four vulnerabilities disclosed by ZDI this week.

Among the other vulnerabilities the company disclosed is a flaw in how IE handles some objects.

“The specific flaw exists within the handling of CAttrArray objects. By manipulating a document’s elements an attacker can force a dangling pointer to be reused after it has been freed. An attacker can leverage this vulnerability to execute code under the context of the current process,” the advisory says. 

The other two vulnerabilities are similar, in that they involve IE mishandling certain objects. IE will in some circumstances mishandle CTreePos and CCurrentStyle objects, leading to a dangling pointer that an attacker can reuse. 

This story was updated on July 23 to add context about the flaws only affecting IE Mobile and the comment from Microsoft.

 

[“source – threatpost.com”]