CVE-2018-7889 in calibre
Summary
by MITRE
gui2/viewer/bookmarkmanager.py in Calibre 3.18 calls cPickle.load on imported bookmark data, which allows remote attackers to execute arbitrary code via a crafted .pickle file, as demonstrated by Python code that contains an os.system call.
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Analysis
by VulDB Data Team • 02/17/2023
The vulnerability identified as CVE-2018-7889 represents a critical remote code execution flaw within the Calibre e-book management software version 3.18. This issue specifically affects the gui2/viewer/bookmarkmanager.py component which processes bookmark data imported by users. The vulnerability stems from the insecure use of cPickle.load() function when handling imported bookmark files, creating an avenue for malicious actors to execute arbitrary code on systems running vulnerable versions of Calibre.
The technical exploitation of this vulnerability occurs through the manipulation of pickle files, which are serialized data formats commonly used for object serialization in python applications. When Calibre processes a crafted .pickle file through the bookmark manager, the cPickle.load() function deserializes the data without proper validation, allowing attackers to inject malicious python code that gets executed within the application context. This particular exploit demonstrates the use of os.system calls within the malicious pickle payload, enabling attackers to execute arbitrary commands on the target system with the privileges of the Calibre application process.
The operational impact of CVE-2018-7889 extends beyond simple code execution, as it provides attackers with full control over affected systems. Since the vulnerability exists within the viewer component of Calibre, attackers could potentially compromise user systems simply by enticing them to import malicious bookmark files. This makes the vulnerability particularly dangerous in environments where users might receive bookmarks from untrusted sources or where automated import mechanisms exist. The attack vector requires minimal user interaction beyond the standard import process, making it an attractive target for social engineering campaigns.
This vulnerability maps directly to CWE-502, which specifically addresses "Deserialization of Untrusted Data" and aligns with ATT&CK technique T1059.006 for "Command and Scripting Interpreter: Python". The flaw demonstrates how insecure deserialization practices can lead to remote code execution and highlights the importance of input validation and secure coding practices in handling serialized data. Organizations using Calibre should consider this vulnerability as part of their broader security posture assessment, particularly in environments where users might import content from external sources or where automated content processing occurs.
The recommended mitigation strategy involves immediate upgrading to Calibre versions that have patched this vulnerability, as the software developers have addressed the insecure deserialization issue by implementing proper input validation and sanitization measures. Additionally, system administrators should implement strict access controls and user education programs to prevent users from importing untrusted bookmark files. Network segmentation and monitoring for suspicious pickle file imports can provide additional layers of defense. Organizations should also consider implementing application whitelisting policies to prevent execution of arbitrary python code through the Calibre application interface. The vulnerability underscores the critical importance of secure coding practices and the potential consequences of improper handling of serialized data in software applications.