Users have another reason to be careful when opening Word attachments sent by email: A researcher has discovered yet another zero-day flaw in the program.
The latest flaw, discovered by a researcher who calls himself "Disco Jonny," is the third Word zero-day found in the past week.
The French Security Incident Response Team (FrSIRT) rated the flaw critical in an advisory Thursday, describing the problem as a memory corruption error that surfaces when malformed documents are handled.
Attackers could exploit the flaw to run malicious commands on a targeted machine by tricking the user into opening a specially crafted Word document.
Disco Jonny included a proof-of-concept exploit in his online analysis.
Microsoft said it is investigating the flaw report. "Upon completion of this investigation, Microsoft will take appropriate action to help protect our customers," a company spokesman said by email. "This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs."
In the meantime, various security organizations are advising people to be cautious when opening email attachments from unknown sources.
Cupertino, Calif.-based antivirus giant Symantec Corp. also emailed customers of its DeepSight threat management service a list of recommended best practices to combat the threat.
The vendor suggested that users:
- Deploy network intrusion detection systems to monitor network traffic for malicious activity.
- Not accept or execute files from untrusted or unknown sources.
- Not follow links provided by unknown or untrusted sources.
- Implement multiple redundant layers of security.