CVE-2015-9278 in MailEnable
Summary
by MITRE
MailEnable before 8.60 allows Privilege Escalation because admin accounts could be created as a consequence of %0A mishandling in AUTH.TAB after a password-change request.
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Analysis
by VulDB Data Team • 05/02/2020
The vulnerability identified as CVE-2015-9278 represents a critical privilege escalation flaw within MailEnable email server software versions prior to 8.60. This vulnerability stems from improper handling of newline characters in the AUTH.TAB file during password change operations, creating a pathway for unauthorized users to elevate their privileges and gain administrative access to the mail server. The issue specifically manifests when the system processes authentication tab files containing null byte sequences that are not properly sanitized or validated.
The technical exploitation of this vulnerability involves manipulating the AUTH.TAB file through carefully crafted password change requests that include %0A sequences representing newline characters. When the mail server processes these malformed requests, it fails to properly validate or sanitize the input, allowing attackers to inject additional administrative account entries into the authentication table. This improper input handling creates a condition where arbitrary user accounts can be granted administrative privileges without proper authentication or authorization mechanisms being enforced.
From an operational perspective, this vulnerability presents a severe risk to organizations relying on MailEnable for their email infrastructure. The privilege escalation capability means that attackers who initially gain access to a low-privilege user account can potentially escalate to full administrative control of the entire mail server. This allows them to read, modify, or delete email messages, create new user accounts, configure server settings, and potentially use the compromised server as a platform for further attacks within the network. The vulnerability's impact extends beyond simple data access as it provides attackers with complete control over the mail server's functionality and configuration.
The vulnerability aligns with CWE-20, which addresses improper input validation, and demonstrates characteristics consistent with CWE-74, indicating improper neutralization of special elements used in data queries. From an ATT&CK framework perspective, this vulnerability maps to T1078 for valid accounts and T1547 for privilege escalation techniques. The exploitation process follows T1078.002, where adversaries use valid accounts to gain access, and T1547.001, where they escalate privileges through system modifications. Organizations should immediately apply the vendor-provided patch for MailEnable version 8.60 or later to remediate this vulnerability.
Mitigation strategies should include immediate patch deployment as the primary defense mechanism, along with network segmentation to limit access to mail server components. Additional security controls should involve monitoring for unusual authentication patterns, implementing strict input validation on all user-facing interfaces, and conducting regular security assessments of mail server configurations. Organizations should also consider implementing multi-factor authentication for administrative accounts and establishing robust access control policies to minimize the impact of potential privilege escalation attempts. Regular security updates and vulnerability management processes should be enforced to prevent similar issues from occurring in the future.