CVE-2002-2228 in Mailscanner
Summary
by MITRE
MailScanner before 4.0 5-1 and before 3.2 6-1 allows remote attackers to bypass protection via attachments with a filename with (1) extra leading spaces, (2) extra trailing spaces, or (3) alternate character encodings that cannot be processed by MailScanner.
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Analysis
by VulDB Data Team • 06/11/2018
The vulnerability described in CVE-2002-2228 represents a significant security flaw in MailScanner email filtering software that affected versions prior to 4.0 5-1 and 3.2 6-1. This issue stems from inadequate input validation mechanisms within the email attachment processing pipeline, specifically targeting how the system handles filename parsing and normalization. The vulnerability operates through a classic race condition and normalization bypass attack vector that exploits the software's failure to properly sanitize and standardize filename representations before applying security checks.
The technical implementation of this vulnerability involves three distinct attack vectors that leverage different aspects of filename processing. First, attackers can insert extra leading spaces in attachment filenames, which MailScanner fails to properly normalize or strip before performing security checks. Second, the vulnerability accepts extra trailing spaces in filenames that similarly bypass security controls due to insufficient whitespace trimming. Third, the flaw allows exploitation through alternate character encodings that MailScanner cannot properly process, creating a scenario where malicious filenames can evade detection mechanisms. This multi-pronged approach demonstrates a fundamental weakness in the software's filename handling architecture and its inability to properly canonicalize input before security validation.
From an operational impact perspective, this vulnerability creates a severe bypass mechanism that allows attackers to circumvent email security protections without requiring authentication or advanced exploitation techniques. The attack can be executed remotely through standard email transmission channels, making it particularly dangerous for organizations that rely heavily on email filtering for malware prevention. The vulnerability essentially allows malicious attachments to be delivered through email systems that should have blocked them, potentially leading to malware delivery, data exfiltration, or further network compromise. The impact extends beyond simple bypass to potentially enabling more sophisticated attacks that rely on email as an initial access vector.
The vulnerability aligns with CWE-180, which addresses "Incorrect Behavior Order" in input validation and canonicalization processes, and represents a classic example of improper input sanitization that allows security controls to be bypassed. From an ATT&CK framework perspective, this vulnerability maps to techniques involving evasion of security controls through input manipulation, specifically T1070.004 for "File and Directory Permissions Modification" and T1566 for "Phishing" through email delivery. Organizations affected by this vulnerability would have experienced reduced email security effectiveness, potentially allowing attackers to deliver malicious payloads that would normally have been detected and blocked by proper filtering mechanisms.
Mitigation strategies for this vulnerability require immediate software updates to versions that properly implement filename canonicalization and input validation. Organizations should implement additional email security layers including content inspection, file type validation, and behavioral analysis to detect anomalous attachment patterns. Network administrators should also configure email systems to enforce strict filename normalization policies and implement redundant security controls that can detect and block suspicious file naming conventions. The fix typically involves implementing proper input sanitization routines that normalize whitespace characters and handle alternate encodings before any security checks are performed, ensuring that all filenames are processed through standardized canonicalization before being evaluated against security policies.