@ wickerman for future reference.
Generally there are three types of scans offered by most anti-virus and anti-malware programs:
- Quick Scan only checks the areas of your computer most likely to contain malware...the most prevalent and common places where malware typically hides. The length of time for performing a Quick scan will vary but it generally takes about 15-30 minutes so they can be performed daily.
- Full Scan is much more comprehensive since it scans the entire hard drive (all folders/files) which can number in the thousands. The length of time for performing a Full scan will also vary but because it is so comprehensive, this type of scan can take several hours. Most Full Scans can be scheduled to run late at night when not using the computer so you can perform a weekly scan without having to monitor it.
- Custom Scan allows the user to select any files and folders on the hard drive to be scanned.
Anti-virus programs can use a scanning engine with Behavioral Analysis
, Heuristic analysis
or a combination of both. Heuristic scanning methods vary depending on the vendor. Some claim to allow emulation of the file's activities in a virtual sandbox
. Others scan the file more intensively, searching line by line inspecting the code in a file to see if it contains virus-like characteristics. If the number of these characteristics/instructions exceeds a pre-defined threshold, the file is flagged as a possible virus
In most cases when performing routine security checks, only a Quick Scan is needed. A Full Scan is recommended for heavily infected systems.
to complete an anti-virus or anti-malware scan depends
on a variety of factors
- The program itself and how its scanning engine is designed to scan: using a signature database vs heuristic scanning or a combination of both.
- Options to scan for spyware, adware, riskware and potentially unwanted programs (PUPS).
- Options to scan memory, boot sectors, registry and alternate data streams (ADS).
- Type of scan performed: Deep, Quick or Custom scanning.
- What action has to be performed when malware is detected.
- A computer's hard drive size.
- Disk size and used capacity (number of files that have to be scanned).
- Types of files (.exe, .dll, .sys, .cab, archived, compressed, packed, email, etc) that are scanned.
- Whether external drives are included in the scan.
- Competition for and utilization of system resources by the scanner.
- Other running processes and programs in the background.
- Whether it stalls, hangs or freezes.
- Interference from malware.
- Interference from other security programs attempting to scan at the same time.
- Interference from other programs attempting update (download/install) components from the Internet.
- Interference from the user (whether or not you use the computer during the scan).
-- Using two security scanning engines at the same time can cause each to interfere with the other, cause systems hangs, false detections, unreliable results and other unpredictable behavior.
-- Although they should not affect an anti-virus scan, if the screensaver, hibernation or Sleep Mode are not turned off before scanning, those features can sometimes have odd effects when attempting to perform a scan. Some folks create special power schemes to use when doing their scans while others just turn these features off until the scan is complete.To speed up a scan
, uninstall unnecessary programs, clean out temporary files
, temporarily disable any other real-time protection tools
, close all open programs, perform a Quick Scan
instead of a Full one and do not use the computer during the scan
. In some case you may need to try scanning in safe mode
However, if the scanner freezes and does not continue any further, you may just have to terminate it and try again.