CVE-2006-0139 in MegaBBS
Summary
by MITRE
The send-private-message functionality (send-private-message.asp) in PD9 Software MegaBBS 2.1 allows remote attackers to read private messages of other users via a modified replyid parameter.
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Analysis
by VulDB Data Team • 07/17/2018
The vulnerability identified as CVE-2006-0139 resides within the PD9 Software MegaBBS 2.1 bulletin board system, specifically targeting the send-private-message functionality implemented in the send-private-message.asp component. This represents a critical access control flaw that fundamentally undermines the security model of the platform's private messaging system. The vulnerability stems from inadequate input validation and improper authorization checks within the application's message handling logic, creating a pathway for unauthorized users to bypass normal access restrictions and gain visibility into private communications between legitimate users.
The technical implementation of this flaw involves the manipulation of the replyid parameter through which the application processes private message requests. When users attempt to reply to private messages, the system relies on the replyid parameter to identify the target message and validate user permissions. However, the application fails to properly authenticate or authorize access to the referenced message, allowing attackers to construct malicious requests with modified replyid values that point to private messages belonging to other users. This parameter manipulation enables attackers to directly access private message content without proper authentication, effectively circumventing the intended privacy controls of the messaging system.
The operational impact of this vulnerability extends beyond simple information disclosure, creating significant risks for user privacy and platform integrity. Attackers can systematically enumerate private messages across the user base, potentially accessing sensitive personal information, confidential communications, or potentially compromising user trust in the platform. The vulnerability affects all users who have private messaging capabilities enabled, making it particularly dangerous in environments where users might share sensitive information through private channels. This flaw directly violates fundamental security principles of confidentiality and access control, as defined by the CWE-284 weakness category, which addresses improper access control mechanisms in software applications. The vulnerability also aligns with ATT&CK technique T1213.002, which covers data from information repositories, as attackers can systematically extract private communications from the message storage system.
The exploitation of this vulnerability requires minimal technical skill and can be accomplished through simple parameter manipulation techniques, making it particularly dangerous in environments where the platform lacks proper security monitoring or intrusion detection systems. Security professionals should consider this vulnerability as a critical concern for any legacy MegaBBS installations, as the flaw represents a fundamental breakdown in the application's security architecture. Organizations should implement immediate mitigations including input validation for all user-supplied parameters, proper session management, and authorization checks that verify user permissions before accessing private message content. The vulnerability also highlights the importance of proper code review and security testing for legacy applications, as similar flaws may exist in other components of the platform. Additionally, this vulnerability demonstrates the critical need for regular security assessments and vulnerability management processes to identify and remediate such access control weaknesses in web applications, particularly those handling sensitive user communications.