CVE-2024-20748 in Acrobat 2020
Summary
by MITRE • 02/15/2024
Acrobat Reader versions 20.005.30539, 23.008.20470 and earlier are affected by an out-of-bounds read vulnerability that could lead to disclosure of sensitive memory. An attacker could leverage this vulnerability to bypass mitigations such as ASLR. Exploitation of this issue requires user interaction in that a victim must open a malicious file.
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Analysis
by VulDB Data Team • 02/15/2024
This vulnerability represents a critical out-of-bounds read flaw in Adobe Acrobat Reader affecting multiple version ranges including 20.005.30539 and 23.008.20470. The technical implementation contains memory access errors where the application fails to properly validate array bounds during file processing operations. When parsing maliciously crafted PDF files, the reader attempts to access memory locations beyond allocated buffers, potentially exposing sensitive data from adjacent memory regions. This type of vulnerability falls under CWE-129 Input Validation and Output Encoding, specifically manifesting as improper validation of buffer boundaries during memory operations.
The operational impact extends beyond simple information disclosure, as this vulnerability can be exploited to bypass critical security mitigations such as Address Space Layout Randomization. The out-of-bounds read allows attackers to potentially extract memory addresses from the process heap or stack, which can then be used in subsequent exploitation attempts. This capability significantly reduces the effectiveness of modern exploit mitigations and makes the system more vulnerable to further attacks. According to ATT&CK framework, this vulnerability maps to T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, as it requires user interaction through opening malicious files.
From a security perspective, the vulnerability requires social engineering to succeed, making it less automated than fully remote exploits but still highly dangerous due to its potential for privilege escalation. The attack vector involves crafting a malicious PDF file that triggers the out-of-bounds read condition when opened by the vulnerable application. This creates an ideal scenario for targeted attacks in enterprise environments where users regularly open PDF documents from external sources or email attachments. The memory disclosure can reveal stack canaries, heap addresses, or other security-related information that would otherwise be protected by modern operating system security features.
Organizations should prioritize immediate patching of all affected versions to prevent exploitation attempts. The mitigation strategy should include regular update management processes and user education regarding the risks of opening untrusted PDF files. Network security controls such as email filtering and web proxy restrictions can provide additional layers of protection while patches are deployed. Security monitoring should focus on detecting unusual file access patterns or memory anomalies that might indicate exploitation attempts. This vulnerability highlights the importance of maintaining current software versions and implementing comprehensive patch management strategies to protect against known vulnerabilities in widely used applications.
The broader implications demonstrate how seemingly simple memory handling errors can create significant security risks, particularly in applications that process untrusted input files. The combination of out-of-bounds read conditions with privilege escalation opportunities makes these vulnerabilities particularly attractive to threat actors seeking persistent access to target systems. Regular security assessments and code reviews focused on memory safety practices are essential for preventing similar issues in other software components. This vulnerability serves as a reminder of the critical importance of robust input validation and proper memory management in security-critical applications.