CVE-2015-1642 is a memory corruption vulnerability in Microsoft Office. CISA added it to the Known Exploited Vulnerabilities catalogue on 3 March 2022, which means attackers have used it in real attacks. Microsoft Office contains a memory corruption vulnerability that allows remote attackers to execute arbitrary code via a crafted document.
What the vulnerability means
Memory corruption in a desktop office suite is dangerous because it can turn a normal-looking document into an execution path. In practice, that means the vulnerability can be triggered through routine user workflows, which makes delivery and exploitation much easier than a flaw that requires unusual access.
The important security property here is not the memory bug itself, but the opportunity it creates for arbitrary code execution. Once an attacker can make Office mis-handle crafted content, the document becomes a vehicle for running code in the victim’s context, which can lead to malware delivery, persistence, or further internal compromise.
Why Microsoft Office memory corruption is risky
Office remains a high-value target because it is widely deployed, handles external content constantly, and is often trusted by users and mail gateways. A memory corruption flaw in this product class is especially attractive because a single successful open action can be enough to start an intrusion chain.
This type of vulnerability is often used in phishing and initial access campaigns, where the attacker’s goal is to move from document delivery to code execution before security tools or users recognise the problem. The NIST National Vulnerability Database and the CVE Program are the authoritative places to confirm record details and follow the vulnerability’s publication trail.
How organisations assess exposure and reduce attack surface
Exposure checking starts with knowing where Microsoft Office is installed, which versions are in use, and which endpoints or virtual desktops routinely open untrusted files. Organisations also need to consider whether users receive documents from email, collaboration platforms, removable media, or partner channels, because those paths increase the practical attack surface.
For exploited vulnerabilities, prioritisation should be driven by asset criticality, internet-facing exposure where relevant, and whether the flaw appears in the CISA KEV catalogue. NHIMG’s Vulnerability Management Guide is useful for translating KEV status into inventory, prioritisation, verification, and remediation workflow.
Detection, containment, and post-exploitation review
After exploitation, defenders should look for suspicious child processes, abnormal document launch behaviour, unusual network connections from Office, and signs that the initial execution step was followed by downloader or payload activity. Memory corruption exploitation often leaves only narrow traces at first, so endpoint telemetry and email-delivery context matter.
If a system may have been compromised, review whether the attacker gained access to mailboxes, browser sessions, saved credentials, or local tokens after execution. When the attack path progresses beyond the workstation, review lateral movement indicators and confirm whether the original document was delivered to other users in the same campaign.
Risk and Threat Considerations
This vulnerability class is high risk because it combines common user behaviour with a reliable execution target. Once a crafted document reaches a mailbox or shared folder, the attacker only needs one successful open action to convert a file-based delivery into code execution and possible foothold establishment.
Failure mechanism: The crafted document drives Office into a corrupted memory state, allowing control-flow redirection or other unsafe execution behaviour that launches attacker-controlled code.
Impact: The immediate impact can range from malware execution to broader compromise of the user endpoint, with potential follow-on theft of data, credentials, or sessions.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-53 Rev 5 and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | SI-2 — Flaw Remediation | Addresses timely remediation of exploited software flaws in Office. |
| SI-3 — Malicious Code Protection | Supports blocking payload delivery and execution from malicious documents. | |
| AU-6 — Audit Record Review, Analysis, and Reporting | Supports review of endpoint and document activity after suspected exploitation. | |
| Recommendation — Prioritise remediation of Office vulnerabilities that are known to be exploited. Harden endpoint protections to detect and block malicious Office-delivered code. Review endpoint telemetry and document-handling events for signs of exploitation. | ||
| CIS Controls v8 | CIS-7 — Continuous Vulnerability Management | Covers inventory, prioritisation, and remediation of exploited software vulnerabilities. |
| CIS-10 — Malware Defenses | Addresses malicious payload delivery after document-triggered code execution. | |
| Recommendation — Track Office exposure and prioritise remediation for KEV-listed vulnerabilities. Detect and contain malware that executes after a crafted Office document is opened. | ||
Practitioner Guidance
Why practitioners should care: Treat exploited Office memory corruption as an endpoint and email-delivery problem, not only a patching problem. If the vulnerable software remains present on high-exposure systems, document handling becomes an attack path that should be assumed active until proven otherwise.
What to watch for: Focus on endpoints that open external documents, especially where user permissions, macro policy, attachment handling, or EDR visibility are weak. A useful operational question is whether the environment can identify and isolate a malicious document before it becomes execution.
Practitioner takeaway: Use the vendor advisory and KEV status to drive prioritisation, then verify exposure by asset inventory and post-event hunting rather than relying on patch deployment alone.
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on October 17, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org