CVE-2017-7229 in O365
Summary
by MITRE
PGP/MIME encrypted messages injected into a Vaultive O365 (before 4.5.21) frontend via IMAP or SMTP have their Content-Type changed from 'Content-Type: multipart/encrypted; protocol="application/pgp-encrypted"; boundary="abc123abc123"' to 'Content-Type: text/plain' - this results in the encrypted message being structured in such a way that most PGP/MIME-capable mail user agents are unable to decrypt it cleanly. The outcome is that encrypted mail passing through this device does not work (Denial of Service), and a common real-world consequence is a request to resend the mail in the clear (Information Disclosure).
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Analysis
by VulDB Data Team • 09/23/2020
The vulnerability identified as CVE-2017-7229 represents a critical flaw in Vaultive O365 versions prior to 4.5.21 that specifically targets the handling of PGP/MIME encrypted email messages within enterprise email security appliances. This issue manifests when encrypted messages are processed through the device's frontend via either IMAP or SMTP protocols, creating a fundamental misclassification of message content that undermines the entire encryption mechanism. The technical nature of this vulnerability lies in the device's improper content-type header manipulation, which fundamentally alters how email clients interpret and process encrypted messages, effectively breaking the PGP/MIME protocol compliance that is essential for secure email communication.
The core technical flaw involves the device's failure to preserve the original Content-Type header structure of PGP/MIME messages during processing. When a message arrives with the proper Content-Type header of 'multipart/encrypted; protocol="application/pgp-encrypted"; boundary="abc123abc123"', the vulnerable device transforms it into a simple 'text/plain' Content-Type header. This transformation occurs at the message processing layer and represents a clear violation of email protocol standards, specifically undermining the MIME structure that PGP/MIME relies upon for proper message parsing and decryption. The vulnerability can be classified under CWE-200 as it exposes information through improper handling of encrypted content, and it aligns with ATT&CK technique T1566 for the use of malicious email content to bypass security controls.
The operational impact of this vulnerability extends beyond simple message corruption to create significant security and usability consequences within enterprise email environments. The Denial of Service aspect occurs because email clients that properly implement PGP/MIME decryption protocols cannot process messages that have had their Content-Type headers altered, resulting in failed decryption attempts and complete message inaccessibility. More critically, this vulnerability leads to information disclosure risks as recipients often must request that senders resend messages in plaintext format, effectively bypassing the encryption that was intended to protect sensitive communications. The real-world implications include increased administrative overhead for users who must repeatedly resend encrypted messages, potential compliance violations in regulated environments where encrypted communications are required, and a degradation of security posture that undermines the trust placed in the email security infrastructure.
Organizations utilizing Vaultive O365 versions before 4.5.21 face substantial risk from this vulnerability, particularly in environments where PGP/MIME encryption is a standard security practice for protecting sensitive communications. The remediation approach requires immediate upgrade to version 4.5.21 or later, which includes proper Content-Type header preservation mechanisms. Additionally, security teams should implement monitoring for unusual patterns in encrypted message processing and consider temporary workarounds such as bypassing the affected device for PGP/MIME traffic or implementing alternative encryption solutions. The vulnerability demonstrates the critical importance of maintaining proper protocol compliance in security appliances and highlights the need for thorough testing of encryption handling capabilities in enterprise security solutions. Organizations should also review their incident response procedures to address potential information disclosure scenarios and ensure that users understand the risks associated with sending encrypted messages through vulnerable systems.