Pierluigi Paganini May 10, 2017

Microsoft Patch Tuesday for May 2017 address tens security vulnerabilities, including a number of zero-day flaws exploited by Russian APT groups.

Microsoft Patch Tuesday updates for May 2017 fix more than 50 security flaws, including a number of zero-day vulnerabilities exploited by Russian APT groups.

Microsoft released security updates for Windows, Internet Explorer, Edge, Office, the .NET framework, and Flash Player on Tuesday.

Security experts at Microsoft worked with peers at ESET and FireEye to address the vulnerabilities affecting Encapsulated PostScript (EPS) filter in Office.

Researchers at FireEye investigated some attacks attributed to the Russian APT groups and also an unknown financially-motivated threat actor.

“At the end of March 2017, we detected another malicious document leveraging an unknown vulnerability in EPS and a recently patched vulnerability in Windows Graphics Device Interface (GDI) to drop malware. Following the April 2017 Patch Tuesday, in which Microsoft disabled EPS, FireEye detected a second unknown vulnerability in EPS.” reads the analysis shared by FireEye.

“FireEye believes that two actors – Turla and an unknown financially motivated actor – were using the first EPS zero-day (CVE-2017-0261), and APT28 was using the second EPS zero-day (CVE-2017-0262) along with a new Escalation of Privilege (EOP) zero-day (CVE-2017-0263). Turla and APT28 are Russian cyber espionage groups that have used these zero-days against European diplomatic and military entities. The unidentified financial group targeted regional and global banks with offices in the Middle East.”

The Turla group (aka Waterbug, KRYPTON, and Venomous Bear) has been exploiting an Office remote code execution (RCE) vulnerability (CVE-2017-0261) to spread the SHIRIME custom JavaScript malware.

A second group of financially motivated threat actors has been exploiting the same vulnerability to deliver a new variant of the NETWIRE malware.

The experts observed that The Turla APT also leveraged CVE-2017-0001 for privilege escalation, while the cyber crime gang the CVE-216-7255 for privilege escalation.

The experts from the two firms confirmed that the notorious APT28 group exploited a number of zero-day vulnerabilities in targeted attacks, including the CVE-2017-0262 Office RCE vulnerabilities and a Windows privilege escalation tracked as CVE-2017-0263.

The hackers leveraged the above exploits to deliver the GAMEFISH malware (Seduploader).

Microsoft announced that the security updates released this month have fixed vulnerabilities in Office (CVE-2017-0261 and CVE-2017-0262) exploited the Russian APT groups.

The list of flaws fixed by Microsoft on Tuesday includes also a memory corruption issue in Internet Explorer tracked as CVE-2017-0222, this memory corruption zero-day can be exploited by a remote attacker for code execution.

Pierluigi Paganini

(Security Affairs – Russian APT groups, APT28)

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