CVE-2017-6200 in Sandstorm
Summary
by MITRE
Sandstorm before build 0.203 allows remote attackers to read any specified file under /etc or /run via the sandbox backup function. The root cause is that the findFilesToZip function doesn't filter Line Feed (\n) characters in a directory name.
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Analysis
by VulDB Data Team • 02/03/2023
The vulnerability identified as CVE-2017-6200 affects Sandstorm versions prior to build 0.203 and represents a critical security flaw in the sandbox backup functionality. This issue enables remote attackers to access arbitrary files within the /etc and /run directories through a carefully crafted exploitation of the findFilesToZip function. The vulnerability stems from insufficient input validation and sanitization within the backup mechanism, creating a path traversal condition that can be exploited without authentication. The attack vector is particularly concerning as it operates entirely through the sandboxed backup function, which is designed to provide secure file handling while maintaining system isolation. This flaw essentially undermines the fundamental security boundaries that the sandbox is intended to enforce, allowing unauthorized access to sensitive system configuration files and runtime data that should remain protected.
The technical root cause of this vulnerability lies in the improper handling of directory names within the findFilesToZip function where line feed characters are not properly filtered or escaped. When an attacker supplies a malicious directory name containing line feed characters, these characters can be interpreted by the underlying system commands or file processing functions, leading to unintended file access patterns. This type of vulnerability aligns with CWE-22 Path Traversal and CWE-77 Command Injection categories, as the unfiltered input allows for manipulation of file system operations. The line feed character injection effectively breaks the intended directory traversal logic, enabling attackers to bypass normal access controls and read files that would otherwise be restricted. The vulnerability demonstrates a classic case of inadequate input sanitization where the system fails to properly validate or escape special characters that have meaning in file system operations, creating an injection point that can be leveraged for information disclosure.
The operational impact of CVE-2017-6200 extends beyond simple information disclosure, as the /etc and /run directories contain critical system configuration data and runtime information that can be exploited for further attacks. Attackers can access sensitive files such as configuration settings, process identifiers, and other runtime data that may reveal system architecture, network configurations, or authentication mechanisms. This vulnerability can be particularly dangerous in multi-tenant environments where Sandstorm instances host multiple applications and users, as it allows unauthorized access to potentially cross-contaminated data. The remote nature of the exploit means that attackers do not require local system access or credentials, making the vulnerability particularly attractive for reconnaissance and privilege escalation activities. From an attacker's perspective, this vulnerability fits within the attack pattern described by MITRE ATT&CK technique T1083 - File and Directory Discovery, as it enables systematic enumeration of sensitive system files.
Mitigation strategies for CVE-2017-6200 primarily involve updating Sandstorm to build 0.203 or later, which contains the necessary patches to properly sanitize directory names and prevent line feed character injection. Organizations should also implement additional monitoring and logging around backup operations to detect anomalous file access patterns. Network segmentation and access controls should be reviewed to limit exposure of Sandstorm instances to untrusted networks. The fix for this vulnerability should be implemented as a priority, as it addresses a direct bypass of sandbox security boundaries that could enable more sophisticated attacks. Security teams should also conduct thorough audits of other functions within Sandstorm that handle file system operations to identify similar input validation issues that might exist in other components of the platform. Regular security assessments and vulnerability scanning should be conducted to ensure that similar issues are not present in other parts of the system architecture, particularly in functions that process user-provided file paths or directory names.