CVE-1999-1246 in Site Server
Summary
by MITRE
Direct Mailer feature in Microsoft Site Server 3.0 saves user domain names and passwords in plaintext in the TMLBQueue network share, which has insecure default permissions, allowing remote attackers to read the passwords and gain privileges.
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Analysis
by VulDB Data Team • 04/20/2026
The vulnerability described in CVE-1999-1246 represents a critical security flaw in Microsoft Site Server 3.0's Direct Mailer feature that fundamentally compromises user authentication credentials through improper data handling practices. This issue specifically affects the TMLBQueue network share where sensitive authentication information is stored in plaintext format, creating an exploitable condition that directly violates fundamental security principles of credential protection. The vulnerability exists within the server-side application logic where user domain names and passwords are written to network shares without adequate encryption or access control measures, making them immediately accessible to any entity with network connectivity to the affected system.
The technical implementation of this flaw stems from insecure default permissions assigned to the TMLBQueue network share, which typically grants excessive access rights to unauthorized users within the network environment. This configuration allows remote attackers to directly access the network share and read the plaintext credentials stored within the queue files, effectively eliminating any security benefits that might have been provided by the authentication mechanisms. The vulnerability operates at the file system level where the application writes user credentials to a shared network location without implementing proper access controls, file permissions, or encryption mechanisms that would normally protect such sensitive information. According to CWE classification, this represents a direct implementation of CWE-312: Cleartext Storage of Sensitive Information, which specifically addresses the storage of confidential data in an unencrypted format.
The operational impact of this vulnerability extends far beyond simple credential theft, as it provides attackers with elevated privileges within the affected system and potentially across interconnected network resources. Once an attacker successfully reads the plaintext passwords from the TMLBQueue share, they can authenticate as legitimate users and gain access to restricted resources, potentially escalating their privileges through additional attack vectors. The remote nature of this vulnerability means that attackers do not require physical access to the system or local network presence, as they can exploit the insecure network share configuration from any location with network connectivity. This vulnerability directly aligns with ATT&CK technique T1566: Phishing for Information, specifically targeting credential harvesting through insecure storage mechanisms rather than traditional phishing approaches, and represents a significant risk to enterprise security infrastructure.
Mitigation strategies for this vulnerability must address both the immediate exposure through insecure network share permissions and the underlying design flaw in how credentials are handled within the application. The primary recommendation involves implementing proper access controls on the TMLBQueue network share to restrict access to only authorized system processes and administrators, while also ensuring that all sensitive data is encrypted both at rest and in transit. Organizations should disable the Direct Mailer feature if it is not actively required, as this eliminates the attack surface entirely. Additionally, implementing proper network segmentation and monitoring for unauthorized access attempts to sensitive network shares can help detect exploitation attempts. The vulnerability underscores the importance of proper security configuration management and demonstrates how default configurations can create dangerous security exposures, particularly in enterprise web server environments where credential management is critical. System administrators must also consider implementing regular security audits of network share permissions and credential storage mechanisms to prevent similar issues from arising in other components of the system infrastructure.