Microsoft Security Essentials (MSE) (previously codenamed Morro) is an antivirus software created by Microsoft that provides protection against viruses, spyware, rootkits, and trojans for Windows XP (x86), Windows Vista (x86 and x64), and Windows 7 (both x86 and x64), free of charge. MSE replaces Windows Live OneCare, a commercial subscription-based antivirus service and Windows Defender, which only protected users from adware and spyware. It is geared for consumer use, unlike Microsoft's upcoming enterprise-oriented product Microsoft Forefront.
Symantec and McAfee, two competing antivirus vendors, responded by claiming that MSE is not comparable with their own offerings. AVG Technologies viewed MSE positively, stating it reinforced the company's ideal of free antivirus software. Reviews were mostly positive, citing its organized interface, low resource usage, and its status as freeware.
MSE is a security suite designed for consumers. It is based on the Forefront Client Security desktop agent[citation needed], but solely provides malware detection and removal and lacks centralized management features. It includes the same anti-malware engine (dubbed "Microsoft Malware Protection Engine", or MSMPENG for short), and virus definitions that all other Microsoft desktop antimalware products share, including Forefront Client Security, Windows Live OneCare, and Windows Defender (Defender excludes the antivirus definitions which are separate from the antispyware definitions).[citation needed] Before installation, MSE checks for the validity of the installed copy of Microsoft Windows. MSE requires no registration or personal information. MSE will disable Windows Defender, as it provides protection against malware, not limited to spyware and adware.
Updates are published three times a day to Microsoft Update. Using default settings, archived files are decompressed, and then scanned. File downloads and e-mail attachments are also scanned. Its Dynamic Signature Service attempts to better identify malicious files by checking for updates if an application exhibits suspicious behavior. Before taking action against a suspect file, MSE prompts for user input. If no response is received in ten minutes, then the suspected malware is handled according to its default action, letting MSE determine what to do with the malware. System Restore points are created before removing found malware.