Adobe Patches Zero-Day Flaw Used by Exploit Kit

Adobe patches 24 vulnerabilities, including a zero-day issue being exploited by the Magnitude Exploit Kit and flaws reported at the Pwn2own contest.

Adobe patches zero day flaw

Adobe released its monthly security patch update for Flash on April 7, five days earlier than originally planned, in order to help remediate the CVE-2016-1019 vulnerability that is already being exploited in the wild. The zero-day issue is, however, only one of 24 vulnerabilities that Adobe is now patching, including four vulnerabilities first publicly demonstrated at the Pwn2own hacking event in March.

The CVE-2016-1019 zero-day issue was originally discovered by a researcher identified only as "Kafeine," who works with security vendor Proofpoint, in coordination with security researcher Genwei Jiang of FireEye. Adobe also credits Google security researcher Clement Lecigne with helping to report the CVE-2016-1019 vulnerability.

According to Adobe's security advisory, CVE-2016-1019 is a type confusion vulnerability that could lead to code execution. CVE-2016-1019 was being used inside of the Magnitude Exploit kit.

According to FireEye, on April 2, Kafeine provided details on a version of the Magnitude Exploit Kit that was originally believed to be exploiting known Adobe Flash vulnerabilities. As it turns out, not all of the vulnerabilities were known, which is how the zero-day issues were discovered.

"Kafeine from Proofpoint contacted us at FireEye to help identify the potential CVEs of a sample," Jiang told eWEEK. "FireEye researchers often help with the analysis of samples and provide additional knowledge to our fellow researchers that better protects customers."

Typically, with any exploit kit, the included exploits are usually known and not zero-day issues.

Exploit kits are so named partly because they are a set of tools—a set of exploits—the composition of which will change over time as some are patched and others are discovered, said Kevin Epstein, vice president, Threat Operations Center, Proofpoint. "Evidence suggests that the value of any kit is related to the efficacy of its tools—which correlates significantly to the 'freshness' of the exploit," Epstein told eWEEK.

Jiang noted that it is true that exploit kits usually contain several exploits to deliver malware, and those exploits will usually be previously known vulnerabilities.

"That said, it has happened before that exploit kits have employed zero-days, but rarely for the Magnitude Exploit Kit," Jiang said.

FireEye's analysis of the CVE-2016-1019 vulnerability shows a coding style similar to one used by the Hacking Team, an Italian cyber-security vendor that was helping governments with surveillance activities and itself was the victim of a breach in July 2015.

"The code layout and some of its functionalities are almost identical to the leaked exploit source of Hacking Team, but there's no evidence to connect the Hacking Team itself," Jiang said. "After the leaks from Hacking Team, exploit writers were able to learn the technique."

Proofpoint also has some indications that CVE-2016-1019 is being used by the Magnitude Exploit kit to deliver ransomware identified as Cerber and Locky. Epstein explained that so-called "drive-by downloads" do not require user action to initiate; unlike attachment-based malware, simply visiting a Website, by browsing to the site or clicking on a URL in email exposes the browser's Adobe Flash Player to the exploit.

"In short, visiting the wrong Website enables an attacker to tell your computer to download and run the ransomware—no user clicking required," Epstein said.

What's not entirely clear at this point is exactly how many users have been victimized by ransomware as a result of the CVE-2016-1019 vulnerability.

"Given its inclusion in an exploit kit, from a general view, there's a high probability of large-scale spread, and other exploit kits will follow suit," Jiang said. "This is why it is good Adobe continues to act so quickly."

Also of note in Adobe's new Flash player update are patches for vulnerabilities that were publicly demonstrated at the Pwn2own hacking challenge, operated by Trend Micro's Zero Day Initiative (ZDI). Adobe credits Yuki Chen of Qihoo 360 Vulcan Team working with Trend Micro's ZDI for reporting three vulnerabilities: the CVE-2016-1015, a type confusion vulnerability that could lead to remote code execution, and CVE-2016-1016 and CVE-2016-1017, both use-after-free memory vulnerabilities.

Adobe also credits Tencent, working with Trend Micro's ZDI, for reporting CVE-2016-1018, a stack overflow vulnerability that could lead to code execution .

Sean Michael Kerner is a senior editor at eWEEK and Follow him on Twitter @TechJournalist.

Sean Michael Kerner

Sean Michael Kerner

Sean Michael Kerner is an Internet consultant, strategist, and contributor to several leading IT business web sites.