CVE-2016-4841 in Mailwise
Summary
by MITRE
Cybozu Mailwise before 5.4.0 allows remote attackers to inject arbitrary email headers.
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Analysis
by VulDB Data Team • 04/21/2017
The vulnerability identified as CVE-2016-4841 affects Cybozu Mailwise versions prior to 5.4.0 and represents a critical security flaw in email header injection mechanisms. This vulnerability enables remote attackers to manipulate email headers through crafted input, potentially leading to various malicious activities including email spoofing, phishing attacks, and content injection. The flaw exists in the email processing pipeline where user-supplied data is not properly sanitized before being incorporated into email headers, creating an avenue for attackers to inject malicious header values that can alter email behavior and appearance.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the Mailwise email processing system. When email messages are processed through the vulnerable version, the application fails to properly escape or filter special characters that are significant in email header construction. This allows attackers to inject additional headers or modify existing ones by embedding control characters or header delimiters within user input fields. The vulnerability specifically targets the email header injection attack vector where malicious content can be inserted into header fields such as subject lines, from addresses, or other header parameters, potentially bypassing email security controls and authentication mechanisms.
From an operational impact perspective, this vulnerability poses significant risks to organizations relying on Cybozu Mailwise for email communication. Attackers could exploit this flaw to create convincing phishing emails by manipulating the sender information, inject malicious content into email headers, or redirect email traffic through crafted header modifications. The vulnerability undermines the integrity of email communications and can lead to successful social engineering attacks, data exfiltration attempts, and reputation damage for affected organizations. Email security systems that depend on header validation for threat detection may be bypassed, creating blind spots in organizational security posture.
The vulnerability aligns with CWE-1104, which describes the weakness of insufficient input validation in header injection scenarios, and maps to ATT&CK technique T1192 for "Phishing with Spoofed Email Headers" and T1071.004 for "Application Layer Protocol: DNS" when header manipulation affects email routing. Organizations should immediately upgrade to Cybozu Mailwise version 5.4.0 or later to address this vulnerability, as the update includes proper input sanitization and header validation mechanisms. Additional mitigations include implementing strict email header validation policies, deploying email security appliances with header inspection capabilities, and conducting thorough security assessments of email processing workflows. Network monitoring should be enhanced to detect unusual header patterns, and email security training should be provided to staff to recognize potential header injection indicators in suspicious communications.