CVE-2018-0791 in Outlook
Summary
by MITRE
Microsoft Outlook 2007, Microsoft Outlook 2010, Microsoft Outlook 2013, and Microsoft Outlook 2016 allow a remote code execution vulnerability due to the way email messages are parsed, aka "Microsoft Outlook Remote Code Execution Vulnerability". This CVE is unique from CVE-2018-0793.
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Analysis
by VulDB Data Team • 01/29/2021
The vulnerability described in CVE-2018-0791 represents a critical remote code execution flaw affecting multiple versions of Microsoft Outlook including 2007, 2010, 2013, and 2016. This security issue stems from improper parsing of email messages within the Outlook application, creating a pathway for attackers to execute arbitrary code on affected systems. The vulnerability specifically impacts the way Outlook handles certain email content structures, particularly those involving rich text formatting and embedded objects that are processed during message rendering. Security researchers identified that when Outlook encounters malformed email messages containing specially crafted payload data, the application's parsing mechanism fails to properly validate input, leading to potential code execution in the context of the current user's privileges.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which addresses out-of-bounds read vulnerabilities. These classifications indicate that the flaw likely involves improper bounds checking during email message parsing operations, where attacker-controlled data can cause memory corruption. The vulnerability operates through the application's rich text processing engine, which is responsible for handling various formatting elements within email messages. When Outlook processes email content containing maliciously crafted elements, particularly those involving embedded objects or specific markup sequences, the parsing logic can be manipulated to overwrite memory locations or execute unintended code paths. This type of vulnerability falls under the ATT&CK framework's technique T1203, which covers exploitation for execution through the manipulation of memory structures and parsing mechanisms.
The operational impact of CVE-2018-0791 extends beyond simple remote code execution, as it provides attackers with a potential foothold for more sophisticated attacks within corporate networks. Since Outlook is widely used across enterprise environments, successful exploitation could lead to complete system compromise, data exfiltration, or lateral movement within network perimeters. The vulnerability is particularly dangerous because it requires no user interaction beyond simply opening the malicious email message, making it an ideal candidate for phishing campaigns and targeted attacks. Organizations using older versions of Outlook face increased risk as these applications may not receive timely security updates, especially in environments where patch management processes are delayed or incomplete.
Mitigation strategies for this vulnerability should include immediate deployment of Microsoft security patches and updates, particularly the cumulative security updates released in January 2018. Organizations should implement email filtering solutions that can detect and block malicious email content before it reaches user inboxes, focusing on identifying suspicious formatting elements and embedded objects that could trigger the parsing vulnerability. Network segmentation and privilege separation can help limit the potential impact if exploitation occurs, while user education programs should emphasize the importance of not opening suspicious emails or attachments. Additionally, implementing security controls such as Outlook's built-in security features, including the use of Protected View for email messages from unknown senders, can provide additional layers of defense. The vulnerability demonstrates the importance of maintaining current security practices and regular patch management, as it represents a classic example of how legacy applications can become attack vectors when security flaws are discovered in widely used software components.