CVE-2018-11724 in Libmobi
Summary
by MITRE
The mobi_pk1_decrypt function in encryption.c in Libmobi 0.3 allows remote attackers to cause a denial of service (heap-based buffer overflow) or possibly have unspecified other impact via a crafted mobi file.
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Analysis
by VulDB Data Team • 03/28/2023
The vulnerability identified as CVE-2018-11724 resides within the Libmobi 0.3 library's encryption.c file, specifically within the mobi_pk1_decrypt function. This flaw represents a critical heap-based buffer overflow that can be exploited through maliciously crafted mobi files, presenting significant security implications for any system processing mobi formatted documents. The vulnerability manifests when the function processes encrypted data without adequate bounds checking, allowing attackers to manipulate memory allocation patterns and potentially execute arbitrary code or cause system instability. The affected library is commonly used in e-book processing applications and mobile device content management systems, making it a prime target for remote exploitation attempts.
The technical implementation of this vulnerability stems from improper input validation within the mobi_pk1_decrypt function where the application fails to properly verify the size of incoming encrypted data before attempting to process it. This weakness creates an opportunity for attackers to craft specially formatted mobi files that contain oversized or malformed data structures, leading to memory corruption when the decryption routine attempts to allocate heap space for processing. The buffer overflow occurs during the heap allocation phase where insufficient bounds checking allows the application to write beyond allocated memory boundaries, potentially overwriting adjacent memory regions and corrupting program execution flow. This type of vulnerability aligns with CWE-121, heap-based buffer overflow, and represents a classic example of inadequate input validation in cryptographic processing functions.
The operational impact of this vulnerability extends beyond simple denial of service, as it could potentially enable remote code execution or information disclosure depending on the target system configuration and memory layout. Attackers exploiting this vulnerability could cause applications using Libmobi 0.3 to crash or behave unpredictably, leading to service disruption for legitimate users. More concerning is the potential for privilege escalation or arbitrary code execution in scenarios where the vulnerable application runs with elevated privileges. Systems processing mobi files from untrusted sources, including email attachments, web downloads, or file sharing platforms, become particularly vulnerable to this attack vector. The vulnerability's exploitation requires remote access through crafted file delivery, making it suitable for widespread deployment in phishing campaigns or automated attack scenarios.
Mitigation strategies for CVE-2018-11724 should prioritize immediate patching of affected Libmobi installations to version 0.4 or later, which includes proper bounds checking and input validation mechanisms. Organizations should implement strict file validation procedures for all mobi content, particularly when processing files from external sources or untrusted users. Network segmentation and access controls can limit the potential impact of exploitation attempts by restricting access to vulnerable applications. Additionally, regular security audits of document processing pipelines should be conducted to identify other potential vulnerabilities in similar cryptographic libraries. System administrators should monitor for exploitation attempts through network intrusion detection systems and implement proper logging of file processing activities to detect anomalous behavior. The ATT&CK framework categorizes this vulnerability under T1203, Exploitation for Client Execution, and T1059, Command and Scripting Interpreter, highlighting the need for comprehensive defensive measures across multiple attack vectors.