Microsoft Excel is prone to a remote code-execution vulnerability. Successfully exploiting this issue allows attackers to corrupt process memory and to execute arbitrary code in the context of targeted users. Note that Microsoft Office applications include functionality to embed Office files as objects contained in other Office files. As an example, Microsoft Word files may contain embedded malicious Microsoft Excel files, making Word documents another possible attack vector.
Run all software as a nonprivileged user with minimal access rights.
Perform all nonadministrative tasks as an unprivileged user with minimal access rights.
Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of suspicious or anomalous activity. This may help detect malicious actions that an attacker may take after successfully exploiting vulnerabilities in applications. Review all applicable logs regularly.
Do not accept or execute files from untrusted or unknown sources.
Users should never accept files from untrusted or unknown sources, because they may be malicious in nature. Avoid opening email attachments from unknown or questionable sources.
Do not follow links provided by unknown or untrusted sources.
Users should avoid websites of questionable integrity. Never follow links supplied by unknown or untrusted sources.
Implement multiple redundant layers of security.
Since this issue may be leveraged to execute code, we recommend memory-protection schemes, such as nonexecutable stack/heap configurations and randomly mapped memory segments. This tactic may complicate exploits of memory-corruption vulnerabilities.
Microsoft has released a security advisory addressing this issue.