CVE-2017-7413 in Groupware Webmail Edition
Summary
by MITRE
In Horde_Crypt before 2.7.6, as used in Horde Groupware Webmail Edition through 5.2.17, OS Command Injection can occur if the attacker is an authenticated Horde Webmail user, has PGP features enabled in their preferences, and attempts to encrypt an email addressed to a maliciously crafted email address.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/27/2022
The vulnerability CVE-2017-7413 represents a critical command injection flaw in Horde_Crypt library versions prior to 2.7.6, which affected Horde Groupware Webmail Edition through version 5.2.17. This security weakness resides in the email encryption functionality and specifically exploits the interaction between PGP encryption features and email address handling within the webmail interface. The vulnerability demonstrates a classic case of insufficient input validation and sanitization in cryptographic operations, where maliciously crafted email addresses can trigger unintended system command execution.
The technical implementation of this vulnerability occurs when authenticated users with PGP encryption enabled attempt to encrypt emails to specially crafted addresses. The flaw stems from improper handling of email address parameters during the encryption process, where user-supplied email addresses are directly incorporated into system commands without adequate sanitization or escaping mechanisms. This creates an environment where attackers can inject malicious command sequences that get executed by the underlying system shell. The vulnerability specifically impacts the PGP encryption functionality within the Horde framework, where email addresses are processed through shell commands that lack proper input validation controls.
From an operational perspective, this vulnerability presents a significant risk to organizations using affected Horde installations, as it requires only authenticated access and leverages existing PGP encryption features. Attackers can exploit this weakness to execute arbitrary commands on the server with the privileges of the web application user, potentially leading to complete system compromise. The attack vector is particularly concerning because it operates within the legitimate email encryption workflow, making it difficult to detect through standard network monitoring. The vulnerability aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and represents a privilege escalation scenario where authenticated users can gain elevated system access through legitimate application features.
The impact extends beyond simple command execution as attackers can potentially access sensitive data, modify system configurations, or establish persistence mechanisms within the compromised environment. Organizations with affected installations face the risk of data breaches, system infiltration, and potential lateral movement within their network infrastructure. The vulnerability's exploitation requires minimal privileges and leverages legitimate application functionality, making it particularly dangerous for email-centric environments where PGP encryption is commonly used for sensitive communications. Mitigation strategies should include immediate patching to versions 2.7.6 and later, along with implementing additional security controls such as input validation, privilege separation, and monitoring for unusual command execution patterns within the webmail environment.
Organizations should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation. The vulnerability demonstrates the importance of secure coding practices in cryptographic libraries and highlights the need for comprehensive input validation even in features that appear benign. Security teams should review their incident response procedures to ensure readiness for potential command injection scenarios and consider implementing web application firewalls to detect and block suspicious command execution patterns. This vulnerability serves as a reminder of the critical importance of validating and sanitizing all user inputs, particularly in applications that interface with system-level operations and cryptographic functions.