CVE-2017-2843 in C1 Indoor HD Camera
Summary
by MITRE
A specially crafted HTTP request can allow for a user to inject arbitrary data in the "msmtprc" configuration file resulting in command execution. An attacker can simply send an HTTP request to the device to trigger this vulnerability.
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Analysis
by VulDB Data Team • 12/09/2022
The vulnerability identified as CVE-2017-2843 represents a critical command injection flaw affecting certain mail transfer agent implementations that utilize the msmtprc configuration file format. This vulnerability resides in the handling of HTTP requests that process user-supplied data without proper validation or sanitization mechanisms. The flaw specifically targets systems where the msmtprc configuration file is used for email relay settings, creating a pathway for remote attackers to inject malicious commands through crafted HTTP requests. The vulnerability operates at the application layer and can be exploited without requiring authentication, making it particularly dangerous in networked environments where such services are exposed to untrusted traffic.
The technical implementation of this vulnerability stems from improper input validation within the HTTP request processing pipeline. When a user submits a specially crafted HTTP request containing malicious data, the application fails to properly sanitize or escape the input before writing it to the msmtprc configuration file. This misconfiguration allows arbitrary data injection into a critical system configuration file that is subsequently processed by the mail transfer agent. The msmtprc file format is commonly used for storing email relay settings and authentication credentials, making it a prime target for exploitation. The flaw essentially creates a persistent command injection vulnerability where attacker-controlled data becomes executable code within the system's email processing framework, directly violating the principle of least privilege and input validation.
The operational impact of CVE-2017-2843 extends beyond simple command execution to encompass complete system compromise and potential lateral movement within affected networks. Once an attacker successfully injects malicious commands into the msmtprc file, they can execute arbitrary code with the privileges of the mail transfer agent process, which typically runs with elevated permissions. This vulnerability can be exploited to establish persistent backdoors, exfiltrate sensitive data, or use the compromised system as a launch point for further attacks. The attack surface is particularly concerning because it can be triggered through simple HTTP requests, making it accessible to attackers with minimal technical expertise. The vulnerability aligns with CWE-74, which describes improper neutralization of special elements in output used by a downstream component, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for command and scripting interpreter.
Mitigation strategies for CVE-2017-2843 require immediate implementation of multiple defensive measures to protect affected systems. Organizations should first apply vendor-provided patches or updates that address the input validation deficiencies in the HTTP request handling code. Network segmentation and firewall rules should be implemented to restrict access to mail transfer agent services, particularly those exposed to external traffic. Input validation should be strengthened at all levels of the application stack, with proper sanitization of user-supplied data before any processing or file write operations. Additionally, monitoring should be enhanced to detect unusual patterns in HTTP request traffic or unexpected modifications to configuration files. The principle of defense in depth should be applied by implementing file integrity monitoring solutions that can detect unauthorized modifications to critical configuration files such as msmtprc. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other applications that may process user input through configuration files, ensuring comprehensive protection against similar command injection attack vectors.