Issues of concern

Performance

Some antivirus software can considerably reduce performance. Users may disable the antivirus protection to overcome the performance loss, thus increasing the risk of infection. For maximum protection, the antivirus software needs to be enabled all the time — often at the cost of slower performance (see also software bloat). asd

Security

Antivirus programs can in themselves pose a security risk as they often run at the 'System' level of privileges and may hook the kernel - Both of these are necessary for the software to effectively do its job, however exploitation of the antivirus program itself could lead to privilege escalation and create a severe security threat. Arguably, use of antivirus software when compared to Principle of least privilege is largely ineffective when ramifications of the added software are taken into account.

When purchasing antivirus software, the agreement may include a clause that the subscription will be automatically renewed, and the purchaser's credit card automatically billed, at the renewal time without explicit approval. For example, McAfee requires one to unsubscribe at least 60 days before the expiration of the present subscription. Norton Antivirus also renews subscriptions automatically by default. For a list of available antivirus softwares and reviews, see www.antivirusnews.net AntivirusNews .

Rogue security applications

Some antivirus programs are actually spyware masquerading as antivirus software. It is best to double-check that the antivirus software which is being downloaded is actually a real antivirus program.

Anti-virus manufacturers have been criticised for fear mongering by exaggerating the risk that virus pose to consumers..

False positives

If an antivirus program is configured to immediately delete or quarantine infected files (or does this by default), false positives in essential files can render the operating system or some applications unusable.

System related issues

Running multiple antivirus programs concurrently can harm performance and create conflicts. It is sometimes necessary to temporarily disable virus protection when installing major updates such as Windows Service Packs or updating graphics card drivers. Active antivirus protection may partially or completely prevent the installation of a major update.