Microsoft on Tuesday released updates to address a total of 130 new security flaws spanning its software, including six zero-day flaws that it said have been actively exploited in the wild.
Of the 130 vulnerabilities, nine are rated Critical and 121 are rated Important in severity. This is in addition to eight flaws the tech giant patched in its Chromium-based Edge browser towards the end of last month.
The list of issues that have come under active exploitation is as follows –
- CVE-2023-32046 (CVSS score: 7.8) – Windows MSHTML Platform Elevation of Privilege Vulnerability
- CVE-2023-32049 (CVSS score: 8.8) – Windows SmartScreen Security Feature Bypass Vulnerability
- CVE-2023-35311 (CVSS score: 8.8) – Microsoft Outlook Security Feature Bypass Vulnerability
- CVE-2023-36874 (CVSS score: 7.8) – Windows Error Reporting Service Elevation of Privilege Vulnerability
- CVE-2023-36884 (CVSS score: 8.3) – Office and Windows HTML Remote Code Execution Vulnerability (Also publicly known at the time of the release)
- ADV230001 – Malicious use of Microsoft-signed drivers for post-exploitation activity (no CVE assigned)
The Windows makers said it’s aware of targeted attacks against defense and government entities in Europe and North America that attempt to exploit CVE-2023-36884 by using specially-crafted Microsoft Office document lures related to the Ukrainian World Congress, echoing the latest findings from BlackBerry.
“An attacker could create a specially crafted Microsoft Office document that enables them to perform remote code execution in the context of the victim,” Microsoft said. “However, an attacker would have to convince the victim to open the malicious file.”
The company has flagged the intrusion campaign to a Russian cybercriminal group it tracks as Storm-0978, which is also known by the names RomCom, Tropical Scorpius, UNC2596, and Void Rabisu.
“The actor also deploys the Underground ransomware, which is closely related to the Industrial Spy ransomware first observed in the wild in May 2022,” the Microsoft Threat Intelligence team explained. “The actor’s latest campaign detected in June 2023 involved abuse of CVE-2023-36884 to deliver a backdoor with similarities to RomCom.”
Recent phishing attacks staged by the actor have entailed the use of trojanized versions of legitimate software hosted on lookalike websites to deploy a remote access trojan called RomCom RAT against various Ukrainian and pro-Ukraine targets in Eastern Europe and North America.
While RomCom was first clocked as a group tied to Cuba ransomware, it has since been linked to other ransomware strains such as Industrial Spy as well a new variant called Underground as of July 2023, which exhibits significant source code overlaps with Industry Spy.
Microsoft said it intends to take “appropriate action to help protect our customers” in the form of an out-of-band security update or via its monthly release process. In the absence of a patch for CVE-2023-36884, the company is urging users to use the “Block all Office applications from creating child processes” attack surface reduction (ASR) rule.
Redmond further said it revoked code-signing certificates used to sign and install malicious kernel-mode drivers on compromised systems by exploiting a Windows policy loophole to alter the signing date of drivers before July 29, 2015, by making use of open-source tools like HookSignTool and FuckCertVerifyTimeValidity.
The findings suggest that the use of rogue kernel-mode drivers is gaining traction among threat actors as they operate at the highest privilege level on Windows, thereby making it possible to establish persistence for extended periods of time while simultaneously interfering with the functioning of security software to evade detection.
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It’s not currently not clear how the other flaws are being exploited and how broadly those attacks are spread. But in light of active abuse, it’s recommended that users move quickly to apply the updates to mitigate potential threats.
Software Patches from Other Vendors
In addition to Microsoft, security updates have also been released by other vendors over the past few weeks to rectify several vulnerabilities, including —