CVE-2015-1770: Microsoft Office Uninitialized Memory Use Vulnerability

CVE-2015-1770 is an uninitialized memory use vulnerability in Microsoft Office. A remote attacker can use a crafted Office document to execute arbitrary code on a system where a user opens or previews that file. For IT and security teams, this matters because Office is widely deployed on endpoints and the attack path is a common document-based vector that can lead to full code execution in the context of the user.

Public detail is limited to the class of flaw and the high-level impact described by CISA. Confirm exact affected products, builds, and fixes against the vendor advisory before prioritizing work.

How it works

The weakness is tracked as CWE-19 (data processing errors) and is described as uninitialized memory use in Microsoft Office. In this class of flaw, the application reads or acts on memory that has not been properly initialized before use. When a crafted Office document is processed, that condition can be abused so that attacker-controlled data influences execution flow, ultimately allowing arbitrary code to run.

Abuse typically requires the victim to open or otherwise cause Office to parse the malicious document. No further exploit mechanics, specific object types, or proof-of-concept details are provided in the given facts; treat any deeper technical claims as unconfirmed until verified against the vendor advisory and your own lab analysis. The outcome of successful exploitation is remote code execution with the privileges of the Office process and the logged-on user.

Am I affected? How to find it in your systems

Microsoft Office commonly runs on Windows endpoints (desktops, laptops, VDI) and may appear in terminal servers or other shared environments where users handle documents. Inventory every host that has Office or related viewers/components installed.

• Use software inventory (SCCM/ConfigMgr, Intune, vulnerability scanners, or package databases) to list Office installations and build numbers.
• Compare those builds to the fixed versions listed in the Microsoft advisory for CVE-2015-1770; do not assume version ranges from secondary sources.
• Check whether users can open documents from untrusted sources (email, downloads, cloud sync, file shares) and whether Protected View or similar mitigations are enabled.
• For exploitation signs, review endpoint telemetry for unexpected child processes of WINWORD.EXE, EXCEL.EXE, POWERPNT.EXE or similar; unusual network connections shortly after document open; and crashes or faulting modules in Office binaries. Correlate with mail gateway and web proxy logs for delivery of suspicious Office files. Absence of known public exploit signatures does not rule out targeted use.

How to remediate

Patch first. Apply the updates Microsoft released for this vulnerability, following the vendor instructions referenced by CISA (“Apply updates per vendor instructions”). Confirm the exact KBs or update channels (MSI, Click-to-Run, etc.) in the official advisory and deploy through your normal test-and-rollout process.

• After patching, verify the installed build numbers match the fixed releases.
• Harden the Office attack surface for this class of issue: keep Protected View enabled for files from the internet and unsafe locations; restrict macros and active content by policy; run Office with least privilege; and ensure users are not routinely operating as local administrators.
• Maintain application allow-listing and attack-surface reduction rules that limit Office from spawning unexpected child processes where your platform supports it.

If you can't patch immediately

Reduce exposure until the vendor update can be applied:

• Segment and limit which endpoints can receive unsolicited Office documents; tighten mail and web filtering to quarantine or sandbox high-risk attachments.
• Enforce Protected View and disable automatic preview panes where policy allows, so untrusted files are not fully parsed without explicit user action.
• Use virtual patching or WAF/email-security rules only as a temporary aid if they can reliably detect the document patterns associated with this issue; confirm rule coverage with your security vendor rather than assuming protection.
• Increase monitoring on Office process trees, script interpreters launched from Office, and outbound connections from user workstations. Alert on anomalies and be prepared to isolate hosts quickly.
• If a specific Office component or feature is confirmed unused and can be disabled without breaking business needs, disable it per vendor guidance until patched.

If your data may have been exposed

Actively exploited document vulnerabilities can lead to endpoint compromise and later data theft or ransomware, though known ransomware use is not documented for this CVE in the provided facts. If you suspect successful exploitation, follow your incident-response process: isolate affected hosts, preserve memory and disk evidence, rotate credentials accessible from those systems, and hunt for persistence and lateral movement. You can also run a free exposure scan of your email addresses against known breach data to see whether associated accounts appear in prior breaches while you complete containment and recovery.