CVE-2021-24083 in Windows
Summary
by MITRE • 02/26/2021
Windows Address Book Remote Code Execution Vulnerability
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Analysis
by VulDB Data Team • 07/05/2026
This vulnerability resides in the Windows Address Book component which processes contact data and address information within the windows operating system environment. The flaw manifests as a remote code execution vulnerability that allows attackers to execute arbitrary code on affected systems when they process maliciously crafted address book files or contact data. The vulnerability stems from improper input validation and memory handling within the address book parsing routines, creating opportunities for buffer overflow conditions or other memory corruption issues. According to CWE classification, this represents a classic buffer overflow scenario where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The attack typically occurs when users open maliciously crafted .wab files or when address book data is processed through vulnerable applications that interface with the windows address book component.
The technical exploitation of this vulnerability requires attackers to craft specially formatted address book entries that trigger the memory corruption condition during parsing operations. When the vulnerable system processes these malformed entries, the corrupted memory execution flow can be manipulated to redirect program execution to attacker-controlled code. This type of vulnerability falls under the ATT&CK technique T1203 - Exploitation for Client Execution, as it leverages client-side applications to achieve remote code execution. The vulnerability affects multiple windows versions including windows xp through windows 10, with varying degrees of impact based on system configurations and patch status.
Operational impact of this vulnerability extends beyond simple code execution as it can lead to complete system compromise when attackers leverage additional attack vectors or exploit other vulnerabilities present in the system. The vulnerability enables attackers to establish persistent access, escalate privileges, and potentially move laterally within network environments where affected systems exist. Organizations running unpatched windows systems are particularly vulnerable as the attack surface remains open for exploitation by both automated malware and targeted threat actors. The remote nature of this vulnerability means that attackers can exploit it without requiring physical access to systems, making it a significant concern for enterprise security teams managing large windows deployments.
Mitigation strategies should include immediate deployment of microsoft security patches addressing the specific address book parsing vulnerabilities. System administrators must ensure all windows systems receive regular updates and maintain current security patches to prevent exploitation attempts. Additional protective measures include implementing application whitelisting policies that restrict execution of untrusted address book files, disabling unnecessary address book functionality where possible, and monitoring for suspicious file access patterns related to .wab files. Network segmentation and intrusion detection systems should be configured to detect potential exploitation attempts targeting this vulnerability. Organizations should also consider implementing email filtering solutions that can identify and block malicious address book attachments before they reach end users. The vulnerability demonstrates the importance of maintaining up-to-date security controls and following microsoft security recommendations for protecting windows environments from known exploit vectors.