CVE-2024-21402 in Outlook
Summary
by MITRE • 02/13/2024
Microsoft Outlook Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 05/21/2026
Microsoft Outlook contains a vulnerability that allows a local attacker to elevate privileges from a standard user to a high integrity level, potentially enabling arbitrary code execution with elevated permissions. This flaw exists in the way Outlook handles certain file operations and process execution contexts within its security model. The vulnerability stems from insufficient validation of file paths and execution contexts when processing specific email attachments or embedded objects within Outlook messages. Attackers can exploit this by crafting malicious email content that, when processed by Outlook, triggers unauthorized privilege escalation. The technical implementation involves manipulation of file handling routines that should normally enforce security boundaries between different integrity levels. This vulnerability affects multiple versions of Microsoft Outlook across different operating systems and is particularly concerning because it can be triggered through normal email processing without requiring any special user interaction beyond opening a malicious message. The flaw represents a classic privilege escalation issue where a standard user process can manipulate system resources that should be restricted to higher privilege contexts. This type of vulnerability is categorized under CWE-269 as "Improper Privilege Management" and aligns with ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation" and T1547.001 which addresses "Registry Run Keys / Startup Folder" as potential exploitation vectors. The impact of this vulnerability extends beyond simple privilege escalation as it can enable attackers to install persistent backdoors, modify system configurations, or access sensitive data that would normally be protected. When exploited successfully, the vulnerability allows attackers to gain elevated system privileges that can be leveraged for further attacks within the network infrastructure. The security implications are particularly severe in enterprise environments where Outlook is widely used and where attackers might leverage this vulnerability to move laterally across the network. Organizations should be aware that this vulnerability can be exploited through social engineering campaigns targeting Outlook users, making it a significant concern for security teams responsible for email security and endpoint protection. The vulnerability's exploitation requires minimal user interaction, typically just opening a malicious email, which makes it particularly dangerous in environments where users may not be fully security-aware. Microsoft has released security updates addressing this vulnerability through regular security patches that modify the privilege handling mechanisms within Outlook's file processing routines. The mitigation strategy involves applying the latest security updates and patches from Microsoft, implementing email filtering solutions that can detect and block potentially malicious content, and conducting regular security awareness training for users to recognize suspicious email patterns. Network segmentation and least privilege access controls can also help reduce the potential impact of successful exploitation by limiting what an attacker can access even with elevated privileges. Security monitoring should include detection of unusual file access patterns and privilege escalation attempts that might indicate exploitation of this vulnerability. The vulnerability demonstrates the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies that include multiple layers of protection against privilege escalation attacks. Organizations should also consider implementing application whitelisting policies that restrict which applications can execute with elevated privileges, further reducing the attack surface for this type of vulnerability.