The Internet Storm Center, an analysis and warning service to Internet users and organizations, on Saturday set its threat Relevant Products/Services level to Yellow, regarding attacks exploiting a vulnerability in all versions of Microsoft's Internet Explorer (IE) browser that was reported last week.

The ISC decided on the Yellow threat level over the weekend after getting reports of attacks on the rise. "The Internet Storm Center is beginning to see increasing evidence of exploits in the wild regarding Microsoft Security Advisory 2887505," a post on the ISC Web site said. "Accordingly, we're moving the InfoCon up to Yellow."

Meanwhile, FireEye, a Milpitas, California-based security Relevant Products/Services company, made note of a campaign targeting organizations in Japan and leveraging the exploit, a campaign that had started in August.

Threat level "Yellow" at the ISC is two levels below ISC's Red, the organization's highest threat level. Yellow means the impact of the threat is either unknown or expected to be minor to the infrastructure Relevant Products/Services. However, local impact could be significant, and users are advised to take actions. Orange signifies a major disruption in connectivity is in progress or imminent. Red means loss of connectivity across a large part of the Internet.

Scanner Sightings

The ISC said, "It appears that an exploit has been in the wild since August 29, 2013 when it was first seen by one of the online security scanners. There is some indication that a weaponized exploit may be in broader circulation now, so expect this to ramp up quickly."

FireEye reported that the campaign, "Operation DeputyDog," bore similarities to infrastructure deployed in the attack Relevant Products/Services on New England company Bit9, a leading provider of software Relevant Products/Services and network Relevant Products/Services security services, earlier this year. FireEye further noted that the DeputyDog attackers have demonstrated "a robust set of malware payloads."

Microsoft has been investigating the reports of the vulnerability and has directed users toward a Microsoft Fix it solution, to be downloaded and run by users, for customer Relevant Products/Services protection Relevant Products/Services until a definitive update is released next month.

The next Patch Tuesday is scheduled for October 8. Some security watchers, however, believe there could be more signs of the exploit in upcoming weeks. If attacks were to rise, Microsoft could possibly deliver an out-of-cycle security update ahead of the patch on October 8. Meanwhile, after Microsoft issued its alert, researchers at Websense estimated that close to 70 percent of Windows-based PCs are vulnerable to the IE zero-day exploit.

Advice for IT Admins

Websense said in its security blog, "While the exploit appears to affect all versions of IE, at the moment, attacks seem to only be targeting users of IE8 and IE9 who are running Windows 7 and XP operating systems."

Websense said it strongly encouraged IT administrators to install the Microsoft Fix it patch while waiting for a formal patch from Microsoft.

Microsoft first issued its security advisory on September 17, telling its customers that under investigation was a "vulnerability in all supported versions of Internet Explorer. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability in Internet Explorer 8 and Internet Explorer 9." Microsoft said that its Fix it solution prevents the exploitation of this issue.

The vulnerability, said the Redmond tech giant, is a remote code execution vulnerability that exists in the way that Internet Explorer accesses an object in memory Relevant Products/Services that has been deleted or has not been properly allocated.

Arbitrary Code

"The vulnerability may corrupt memory in a way that could allow an attacker to execute arbitrary code in the context of the current user within Internet Explorer," said Microsoft. "An attacker could host a specially crafted Web site that is designed to exploit this vulnerability through Internet Explorer and then convince a user to view the Web site."

Microsoft said its action plans may include providing a solution through its monthly security update release process, "or an out-of-cycle security update, depending on customer needs."