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A new Proof of Concept (PoC) has been released by a researcher at Numen Cyber Technology regarding the exploitation of a vulnerability that targets the Windows Win32K subsystem to enable privilege escalation and malicious code execution for attackers. This vulnerability was identified to be actively exploited and has been patched along with two other zero-day vulnerabilities. However, further details on these incidents have not been released.
The vulnerability takes advantage of an issue found in older Windows operating systems with the locking of the ‘nested menu object’ which can be hijacked to gain the same privileges as the application using the object.
This flaw can serve as a method for malicious actors to launch further exploitation through their newly gained privileges. The incidents where it was discovered serve as an example of how this is a serious threat to any unpatched legacy systems used within an organisation’s network.
In the event of a successful execution of this vulnerability, it would give threat actors a high level of privileges to launch an array of malicious actions that could potentially go unnoticed. Although this vulnerability does not directly damage or impact the victim’s system it can be used to enable an array of sophisticated attacks for the theft or destruction of vital organisational data.
A comprehensive endpoint detection and response (EDR) solution, such as Microsoft Defender, can provide additional protection against ransomware threats such as Win32k. EDRs can alert system users of potential breaches and prevent further progress, prior to the malware being able to implement significant damage.
Containment, Mitigations & Remediations
As mentioned previously, it is recommended that an EDR solution is implemented which will allow for the prevention or mitigation of potential attacks from a wide range of threats in real time.
All devices should implement the most recent vendor updates available as these will contain updates to their security features to help prevent exploitation from known threats.
If any suspicious read/write activity relating to Window objects is observed this should be investigated as it may be associated with the vulnerability.
Indicators of Compromise
No specific Indicators of Compromise (IoCs) are available currently.
Win32k is one of many active zero-day exploits that take advantage of unintended functionality of applications or operating systems that can be used to directly exploit or enable the launch of various malicious activity. The main appeal of zero-day exploitations relates to them being unknown to the application vendors until they are discovered, which allows for detection evasion.
No attribution to specific threat actors or groups has been identified at the time of writing.
T1068 – Exploitation for Privilege Escalation