CVE-2020-15908 in cbang
Summary
by MITRE
tar/TarFileReader.cpp in Cauldron cbang (aka C-Bang or C!) before 1.6.0 allows Directory Traversal during extraction from a TAR archive.
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Analysis
by VulDB Data Team • 07/23/2020
The vulnerability identified as CVE-2020-15908 affects the Cauldron cbang library, specifically within the tar/TarFileReader.cpp component, and represents a critical directory traversal flaw that enables arbitrary file system access during TAR archive extraction operations. This issue exists in versions prior to 1.6.0 of the C-Bang library, which is commonly used for various software development projects requiring robust archive handling capabilities. The flaw stems from inadequate validation of file paths within TAR archives, allowing maliciously crafted archive entries to escape the intended extraction directory and write files to arbitrary locations on the target system.
The technical implementation of this vulnerability occurs when the TarFileReader processes archive entries without properly sanitizing or validating the file paths contained within the TAR archive. When extracting files, the software fails to check whether the destination path contains directory traversal sequences such as ../ or ..\ that would allow the extracted file to be placed outside the designated extraction directory. This weakness enables attackers to craft malicious TAR archives containing entries with such traversal sequences, potentially leading to overwriting of critical system files, execution of malicious code, or unauthorized access to sensitive data. The flaw specifically manifests in the handling of absolute paths and relative paths containing traversal components, making it particularly dangerous in environments where archives are extracted with elevated privileges.
The operational impact of this vulnerability extends beyond simple file system manipulation to encompass potential system compromise and data exfiltration scenarios. Attackers could exploit this weakness to place backdoor files in system directories, modify configuration files, or inject malicious code into legitimate applications. In environments where the cbang library is used for automated deployment processes, package management, or software distribution, this vulnerability could enable persistent access or privilege escalation. The vulnerability aligns with CWE-22 Directory Traversal and is consistent with ATT&CK technique T1059 Command and Scripting Interpreter, as it enables adversaries to execute arbitrary code through file system manipulation. The risk is amplified when the affected software extracts archives from untrusted sources, such as user uploads, third-party packages, or network downloads, making it a particularly dangerous flaw in web applications and service environments.
Mitigation strategies for CVE-2020-15908 primarily focus on upgrading to cbang version 1.6.0 or later, which contains the necessary patches to properly validate and sanitize file paths during TAR archive extraction. Organizations should conduct comprehensive vulnerability assessments to identify all systems utilizing vulnerable versions of the cbang library and prioritize remediation efforts accordingly. Additional protective measures include implementing strict file path validation at the application level, restricting archive extraction privileges, and employing sandboxing techniques when processing untrusted archives. Network segmentation and access controls should be enforced to limit the potential impact of successful exploitation attempts, while monitoring systems should be configured to detect unusual file system modifications that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation in archive handling components and serves as a reminder of the security implications of inadequate path sanitization in file system operations.