CVE-2018-0528 in Office
Summary
by MITRE
Cybozu Office 10.0.0 to 10.7.0 allows authenticated attackers to bypass authentication to view the schedules that are not permitted to access via unspecified vectors.
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Analysis
by VulDB Data Team • 02/21/2020
The vulnerability identified as CVE-2018-0528 affects Cybozu Office versions 10.0.0 through 10.7.0, representing a critical authorization bypass flaw that enables authenticated attackers to access restricted schedule information. This issue stems from insufficient access control mechanisms within the application's permission system, allowing malicious users with valid credentials to circumvent the intended security boundaries that should protect sensitive calendar data from unauthorized viewing. The vulnerability specifically targets the scheduling module's authorization logic, where proper validation of user permissions fails to adequately verify access rights before granting schedule visibility.
The technical implementation of this flaw involves unspecified vectors that likely exploit weaknesses in the application's role-based access control (RBAC) mechanisms or session management components. Attackers can leverage their authenticated status to manipulate access requests or exploit inconsistencies in how the system validates user privileges against schedule entries. This type of vulnerability typically falls under CWE-284, which addresses improper access control, and may also relate to CWE-285, addressing improper authorization within the application's permission architecture. The vulnerability's impact extends beyond simple information disclosure, as schedule data often contains sensitive personal and business information that could be used for social engineering, business intelligence gathering, or targeted attacks against individuals or organizations.
From an operational perspective, this authentication bypass represents a significant security risk that could compromise organizational privacy and potentially lead to business disruption. The vulnerability affects the confidentiality aspect of the CIA triad by allowing unauthorized access to sensitive schedule information, which may include meeting details, personal information, business strategies, or other proprietary data. Attackers could exploit this weakness to gain insights into organizational structures, key personnel availability, business plans, or sensitive project timelines, potentially enabling more sophisticated attacks such as spear-phishing campaigns or physical security breaches. The attack vector likely involves manipulating session tokens, API calls, or direct access to schedule viewing functions, with the ATT&CK framework categorizing this under privilege escalation or credential access techniques.
Mitigation strategies for CVE-2018-0528 should focus on implementing robust access control validation mechanisms, including strengthening the application's permission checking logic and ensuring proper session management. Organizations should immediately update to the latest available version of Cybozu Office that addresses this vulnerability, as vendors typically release patches that correct the authorization bypass flaws. Additional defensive measures include implementing network segmentation to limit access to schedule systems, conducting regular security audits of access control mechanisms, and establishing monitoring for unusual access patterns to calendar data. Security teams should also consider implementing multi-factor authentication for schedule access, regular privilege reviews, and comprehensive logging of access attempts to detect potential exploitation attempts. The vulnerability demonstrates the importance of thorough security testing of access control mechanisms and highlights the need for continuous security assessments to identify and remediate authorization bypass vulnerabilities before they can be exploited by malicious actors.