Windows 0-Day Exploit Used In Recent Wave Of PoS Attacks

More than 100 organizations in the hospitality, restaurant, and retail sectors fell victim to a financially motivated spearphishing campaign earlier this year.

At least some of the victims were further compromised by a Windows zero-day privilege escalation exploit that allowed the attackers to gain administrator privileges on Windows machines that served a variety of purposes. The infected Windows machines included several point-of-sale systems, security vendor FireEye warned this week.

FireEye could not confirm if the campaign was related to reports of a PoS system breach at Wendy’s this week affecting some 300--about 5%--of the fast food chain’s 5,500 restaurants.

“Over the past two months, we observed the threat actor gain access to over 100 victim environments by sending out weaponized Word documents with malicious macros,” says FireEye vice president Charles Carmakal.

Those who ran the macros infected their machines with a dynamic-link library downloader dubbed PUNCHBUGGY, designed to download additional malware over HTTPS on the victim’s computer. If the victim computer did not provide system-level access to the downloader, the threat actors employed the Windows 0-day exploit to gain that access and to obtain local and domain credentials.

“With local administrator or domain credentials, the threat actor moved laterally to other systems within the environment,” Carmakal says. The operators of the malware campaign then used the downloader to deploy a memory-scraping tool called PUNCHTRACK on the victim’s network for identifying systems handling payment card data and to steal Track 1 and Track 2 card data from them.

“The escalation of privilege exploit was primarily used to elevate privileges when PUNCHBUGGY was deployed as a non-administrator user,” he says. The exploit was not specific to PoS systems and worked across different systems. “It was used for both lateral movement and installing payment card data scrapers," he says.

The 0-day exploit basically took advantage of a now-patched critical vulnerability (CVE-2016-0167) in the Microsoft Graphics Component in all supported Windows versions and some other Microsoft software. FireEye reported the problem to Microsoft earlier this year and a patch for it was issued last month.

However, the security vendor waited until further fixes become available for the vulnerability in Microsoft’s May security bulletin before publicly disclosing details of the 0-day exploit, Carmakal says.

News of the Windows 0-day exploit that FireEye discovered coincided this week with a report from Symantec about a now-patched 0-day flaw (CVE-2016-0189) in Internet Explorer that the security vendor said has been exploited in limited fashion in South Korea.

Symantec described the flaw as a remote memory corruption vulnerability affecting the IE scripting engine. The exploit appears to have been distributed via a malicious link in a phishing email and also as a download hosted on a compromised site, the vendor said.

The IE 0-day builds on the growing number of previously unreported flaws that attackers have discovered and gone after in recent months. Symantec’s latest Internet Security Threat Report shows that a total of 54 zero-day vulnerabilities were reported in 2015, up a startling 125% from the 24 zero-days reported in 2014.

The unexpected spike shows that uncovering zero-day vulnerabilities and exploiting them has become a "go-to" activity for advanced attackers, Symantec noted in its report. Most of the zero-days were reported in older technologies that have been targeted for a long time, Symantec said, pointing to ten that were found in Adobe’s Flash Player and ten zero-days in Microsoft’s Windows, IE, and Microsoft Office products.

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