CVE-2018-13034 in Web Framework
Summary
by MITRE
Directory traversal in Jester web framework 0.2.0 allows remote attackers to fetch files in arbitrary locations via "..%f" sequences.
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Analysis
by VulDB Data Team • 03/03/2020
The vulnerability identified as CVE-2018-13034 represents a critical directory traversal flaw within the Jester web framework version 0.2.0. This issue stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before processing file requests. The vulnerability specifically manifests when the framework encounters "..%f" sequences in file paths, which are commonly used to navigate up directory levels in file systems. Such sequences, when improperly handled, can allow attackers to access files outside the intended web root directory, potentially exposing sensitive system information.
The technical exploitation of this vulnerability occurs through manipulation of URL parameters or file path inputs that are processed by the Jester framework. When the framework processes these malicious sequences without proper validation, it fails to normalize or sanitize the path components, allowing the traversal logic to interpret the encoded sequences as legitimate navigation commands. This flaw falls under the CWE-22 category of Improper Limitation of a Pathname to a Restricted Directory, which is a well-documented weakness in web application security. The vulnerability creates a direct pathway for attackers to bypass normal access controls and retrieve files from arbitrary locations on the server filesystem.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially lead to complete system compromise. Attackers can leverage this flaw to access configuration files, database credentials, application source code, and other sensitive artifacts that may contain authentication tokens, encryption keys, or other critical system information. The vulnerability enables unauthorized access to files that should remain protected within the application's designated directory structure, potentially leading to further exploitation opportunities such as code execution or privilege escalation. This type of vulnerability is particularly dangerous in environments where the web application has elevated privileges or access to sensitive data repositories.
Security practitioners should implement multiple layers of mitigation for this vulnerability. The primary defense mechanism involves implementing strict input validation and sanitization for all file path parameters, ensuring that any occurrence of directory traversal sequences is properly rejected or normalized. Additionally, the framework should be updated to version 0.2.1 or later, which includes the necessary patches to address this specific issue. Organizations should also consider implementing web application firewalls that can detect and block suspicious path traversal patterns, as well as conducting regular security assessments to identify similar vulnerabilities in other web frameworks or application components. The ATT&CK framework categorizes this vulnerability under the T1083 technique of File and Directory Discovery, which represents a common reconnaissance phase that attackers use to gather information about the target system's file structure and potentially identify additional attack vectors.