CVE-2017-2842 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
This vulnerability resides in the Microsoft Windows Mail and Calendar applications that utilize the msmtp email client for sending messages. The flaw manifests as a command injection vulnerability in the msmtp configuration file processing mechanism, specifically within the msmtprc file handling functionality. The vulnerability stems from insufficient input validation and sanitization of HTTP requests that are processed by the Windows Mail application when configured to use msmtp as the underlying email transfer agent. When a user receives an email with specific formatting or content that triggers the msmtp configuration file update process, the application fails to properly validate or escape the data being written to the msmtprc file, creating a path for arbitrary command execution. The vulnerability is particularly dangerous because it can be triggered remotely through HTTP requests without requiring authentication, making it a critical remote code execution vulnerability that affects Windows 10 and Windows Server 2016 systems. The flaw allows an attacker to inject malicious commands into the configuration file that will be executed when the msmtp client attempts to send emails through the compromised configuration. This vulnerability is classified as a command injection issue under CWE-77 and represents a privilege escalation vector that can be exploited through the ATT&CK technique T1059.001 for command and script injection.
The technical implementation of this vulnerability occurs when the Windows Mail application processes an HTTP request containing specially crafted data that gets written to the msmtprc configuration file. The application does not properly sanitize or validate the input data before writing it to the configuration file, allowing an attacker to inject malicious commands that will execute when the email client attempts to send messages. The msmtprc file is typically located in the user's application data directory and contains email server configuration settings including authentication credentials and server parameters. When the vulnerable application processes an HTTP request that includes command injection payloads, these commands are written directly to the configuration file and subsequently executed by the msmtp client. The vulnerability is particularly insidious because it can be triggered by simply sending an email to a user with a maliciously crafted message that contains the injection payload. The attack requires no user interaction beyond receiving the email, making it a highly effective vector for automated exploitation. The configuration file injection allows for arbitrary command execution in the context of the user account running the Windows Mail application, potentially providing attackers with access to sensitive data, network reconnaissance capabilities, or further system compromise.
The operational impact of this vulnerability extends beyond simple command execution as it provides attackers with a persistent foothold on compromised systems. Once executed, the injected commands can perform various malicious activities including data exfiltration, establishing backdoors, or further compromising the system through privilege escalation. The vulnerability affects all versions of Windows 10 and Windows Server 2016 that have the Windows Mail application installed and configured to use msmtp for email transmission. The remote nature of the exploit means that attackers can compromise systems without requiring physical access or network credentials, making it particularly dangerous for enterprise environments where email systems are heavily utilized. The vulnerability can be exploited by sending an HTTP request containing maliciously crafted data that will be written to the msmtprc file during normal email processing operations. This creates a persistent threat vector that can be leveraged for extended periods without detection, as the malicious commands are embedded within legitimate email processing flows. The configuration file injection technique allows for sophisticated attacks including the installation of additional malware, modification of system settings, or creation of persistent access mechanisms that can survive system reboots.
Mitigation strategies for this vulnerability require immediate patching of affected systems through Microsoft security updates, as the vulnerability was addressed in the July 2017 security updates. Organizations should implement network segmentation to limit access to email servers and reduce the potential attack surface for exploitation attempts. Monitoring for suspicious HTTP requests and email processing activities can help detect exploitation attempts, though the vulnerability's remote nature makes detection challenging. The use of email filtering solutions and sandboxing techniques can provide additional protection against malicious email content that may trigger the vulnerability. System administrators should also review and restrict write permissions to the msmtprc configuration files and related application directories to limit the potential impact of successful exploitation. Implementing the principle of least privilege and ensuring that email applications run with minimal required permissions can reduce the potential damage from successful exploitation attempts. Additionally, network-based intrusion detection systems should be configured to monitor for patterns consistent with the exploitation of this vulnerability, including unusual HTTP request patterns and file modification activities in user application directories. Organizations should also consider implementing application whitelisting policies to prevent execution of unauthorized commands through the vulnerable email processing mechanisms. The vulnerability's classification as a command injection issue under CWE-77 emphasizes the need for comprehensive input validation and sanitization across all email processing components.