CVE-2018-12418 in Junrar
Summary
by MITRE
Archive.java in Junrar before 1.0.1, as used in Apache Tika and other products, is affected by a denial of service vulnerability due to an infinite loop when handling corrupt RAR files.
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Analysis
by VulDB Data Team • 03/27/2023
The vulnerability identified as CVE-2018-12418 represents a critical denial of service flaw within the Junrar library version 1.0.0 and earlier, which is widely utilized by Apache Tika and numerous other applications for handling RAR archive files. This issue stems from improper handling of malformed or corrupt RAR file structures, specifically within the Archive.java component that processes archive metadata and file extraction operations. The flaw manifests when the library encounters RAR files with corrupted internal structures or invalid metadata that trigger an infinite loop during parsing operations, effectively consuming system resources and rendering the application unresponsive.
The technical implementation of this vulnerability resides in the archive parsing logic where the Junrar library fails to properly validate or handle malformed RAR file headers and directory structures. When processing a specially crafted corrupt RAR file, the library enters an infinite loop during the extraction or metadata parsing phase, typically triggered by malformed central directory entries or recursive references within the archive structure. This behavior directly maps to CWE-835, which specifically addresses infinite loops or iterations without proper exit conditions, making it a clear example of insufficient loop termination logic. The vulnerability affects the core parsing functionality that Apache Tika and other applications rely upon to extract content from RAR archives, creating a chain reaction that can impact any system utilizing these components.
From an operational perspective, this vulnerability presents a significant risk to systems that process untrusted RAR files, particularly those handling user-uploaded content or automated archive processing workflows. An attacker could exploit this weakness by submitting a maliciously crafted RAR file that triggers the infinite loop, causing the target application to consume excessive CPU resources and potentially leading to complete service unavailability. The impact extends beyond individual application crashes to potentially affect entire systems or services, especially when multiple concurrent requests are processed or when the vulnerable components are part of critical infrastructure. Systems running Apache Tika for document processing, content management platforms, or any application that relies on RAR extraction capabilities are particularly vulnerable to this type of resource exhaustion attack.
The mitigation strategy for CVE-2018-12418 involves immediate upgrading of the Junrar library to version 1.0.1 or later, which contains the necessary fixes for proper handling of malformed RAR files. Organizations should also implement input validation and sanitization measures to prevent processing of suspicious archive files, alongside implementing resource limits and timeout mechanisms to prevent indefinite resource consumption. Security practitioners should consider deploying network-based intrusion detection systems that can identify and block suspicious RAR file processing patterns, while also ensuring that all affected applications are regularly updated and monitored for similar vulnerabilities. This vulnerability aligns with ATT&CK technique T1499.004, which involves resource exhaustion attacks targeting application availability, and represents a common pattern of denial of service vulnerabilities in archive processing libraries that should be addressed through proper defensive coding practices and regular security updates.