CVE-2015-3326 in ScanMail for Microsoft Exchange
Summary
by MITRE
Trend Micro ScanMail for Microsoft Exchange (SMEX) 10.2 before Hot Fix Build 3318 and 11.0 before Hot Fix Build 4180 creates session IDs for the web console using a random number generator with predictable values, which makes it easier for remote attackers to bypass authentication via a brute force attack.
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Analysis
by VulDB Data Team • 05/17/2022
The vulnerability identified as CVE-2015-3326 affects Trend Micro ScanMail for Microsoft Exchange versions 10.2 prior to Hot Fix Build 3318 and 11.0 prior to Hot Fix Build 4180. This security flaw resides in the web console authentication mechanism where session identifiers are generated using a random number generator that produces predictable values. The weakness stems from insufficient entropy in the random number generation algorithm, creating a significant security risk that undermines the authentication process.
The technical implementation of this vulnerability involves the use of a predictable random number generator for session ID creation within the web console interface. When session identifiers are generated using predictable sequences rather than cryptographically secure random number generators, attackers can effectively guess valid session tokens through brute force methods. This weakness directly violates the principles of secure session management as outlined in CWE-330, which addresses the use of insecure random number generators in security-critical contexts. The vulnerability creates a direct path for unauthorized access to administrative functions that should remain protected from unauthenticated users.
The operational impact of this vulnerability is substantial as it enables remote attackers to bypass authentication mechanisms without requiring valid credentials or exploiting other attack vectors. An attacker can systematically guess session IDs and gain unauthorized access to the ScanMail web console, potentially leading to full administrative control over the email security appliance. This access could allow for configuration changes, data exfiltration, or the deployment of malicious configurations that compromise the entire email infrastructure. The vulnerability particularly affects organizations that rely on ScanMail for Exchange as their primary email security solution, making it a critical target for adversaries seeking persistent access to email systems.
Mitigation strategies for CVE-2015-3326 involve implementing immediate patches and updates from Trend Micro to address the specific random number generation issue in the affected versions. Organizations should ensure that all systems are updated to the latest hot fix builds that contain proper cryptographic random number generation for session ID creation. Network segmentation and access controls should be implemented to limit exposure of the web console to trusted networks only. Additionally, monitoring for suspicious authentication attempts and session management activities can help detect potential exploitation attempts. This vulnerability aligns with ATT&CK technique T1078 which covers legitimate credentials use and T1566 which covers credential harvesting through various attack vectors. The remediation process should include comprehensive testing to verify that the patched implementation generates cryptographically secure session identifiers and that all existing sessions are invalidated during the update process to prevent session fixation attacks.