Eight vulnerabilities have recently been discovered in Microsoft applications tailored for macOS, potentially enabling attackers to exploit these weaknesses for elevated privileges and unauthorized access to sensitive user data. This circumvention directly undermines the operating system’s permissions framework, specifically the Transparency, Consent, and Control (TCC) model designed by Apple.
Security researchers from Cisco Talos emphasized the gravity of these vulnerabilities, noting that successful exploitation could allow attackers to gain any existing permissions granted to the Microsoft apps in question. For instance, this would vastly open the door for malicious activities such as sending emails from the victim’s account without their knowledge, recording audio, capturing images, or even filming videos without any interaction from the user. The affected applications include major Microsoft products like Outlook, Teams, Word, Excel, PowerPoint, and OneNote.
The vulnerabilities arise chiefly from the possibility of injecting malicious libraries into these applications, thus leveraging their entitlements and user-approved permissions. Such a scenario raises significant concerns regarding the security of sensitive information, depending on the permissions assigned to these widely used tools.
TCC is a critical framework established by Apple to manage application access to sensitive user information on macOS. It empowers users with improved visibility over how their data is accessed and utilized by various installed applications. TCC operates using an encrypted database that meticulously records the permissions granted, ensuring consistency across the system.
The efficacy of TCC is augmented through application sandboxing, which restricts a program’s access to system resources, thereby adding an essential layer of security. According to Huntress, this mechanism is crucial as it ensures that applications can only access data for which explicit user consent has been obtained.
Moreover, sandboxing serves as a defense against code injection, which allows attackers to insert harmful code into legitimate application processes, compromising sensitive data. The technique of library injection, also referred to as Dylib Hijacking in macOS environments, poses a unique threat, as it involves embedding code directly into the running processes of applications.
Despite macOS’s robust protective features like hardened runtime, which minimize the risk of such code being executed, the potential for exploitation remains if a malicious actor is able to inject code into the running application. This injected library would inherit all permissions granted to the original process, effectively acting on its behalf.
It is important to underscore that successful execution of this type of attack necessitates the threat actor to have an initial level of access to the compromised host. This access can then be manipulated to open privileged applications and execute the library injection, which can ultimately breach user trust and access sensitive information without their consent.
Furthermore, vulnerabilities can arise when trusted applications load libraries from locations susceptible to tampering, particularly when application settings permit library validation to be bypassed. Microsoft has categorized these issues as “low risk,” as the functionality to load unsigned libraries is often necessary for plugin support. Nonetheless, the company has undertaken measures to address the vulnerabilities highlighted in its OneNote and Teams applications.
As the landscape of vulnerabilities evolves, Microsoft products could inadvertently provide a pathway for attackers to gain comprehensive access to permissions, thereby acting as a conduit for unauthorized actions and breaching the established security model. The complexity of navigating safe plugin management within macOS further complicates this issue. While notarizing third-party plugins is an option, it presents significant logistical challenges, requiring extensive verification of security measures by either Microsoft or Apple.
In summary, the identified vulnerabilities pose significant risks to users of Microsoft applications on macOS, allowing attackers to leverage existing permissions and bypass established security protocols. Business owners should remain vigilant and consider strengthening their cybersecurity measures in light of these findings, using frameworks like MITRE ATT&CK to enhance their understanding of potential adversary tactics.
