Recognizing Computer Threats – Malware

By Chris Williams

Why is my PC running so slowly?

Could it be malware? Some non-malicious events can certainly make your Windows computer run slowly. Such causes range from operating system updates downloading from Microsoft at inopportune times, unnecessary processes/services running in the background, disk fragmentation, or it could just be overdue for a restart (this fixes more ailments than you might think!).

However, if you’re fairly certain it isn’t any of these issues, or if you’re just more paranoid than most, the next several paragraphs detail some things to look at which you can easily access via the Resource Monitor. Keep in mind, that the more you understand about the computer’s performance under normal conditions, the more likely you’ll be able to spot malicious activity taking place. For example, many Windows users have a fairly good idea of how much storage space is left on their computers; this is certainly useful information to have for normal day-to-day operations of the machine. Same holds true when it comes to monitoring how much memory, CPU time, or bandwidth is being utilized.

Consistently High CPU Usage

Malware tends to consume a significant amount of CPU time, so if your CPU Usage meter is consistently pegged at close to 100% it could be an indication of malware infection. Looking at the CPU Usage History can help differentiate if it’s just a short-term spike as opposed to something that’s been going for a longer time frame. We recommend scanning for malware, in particular if your CPU time doesn’t fall to a normal level after a period of relative inactivity.

Memory (RAM) Allocation

Malicious software can run processes in the background that require noticeable amounts of memory, as well as spawning related services that you may not recognize. One approach is to (with as few open applications as possible) make note of any processes or services you are suspicious of, and simply Google them. You will likely find a lot of info regarding Windows system processes as well as services that are related to legitimate applications; in the event that you discover a process that appears to be malicious, it’s important to conduct a thorough malware scan immediately.

Missing Disk Space

Viruses are self-replicating and can, if left unchecked, take up a sizable portion of disk space within a short period of time. This adversely affects the computer’s performance because, as the disk’s capacity approaches its limit, the read/write speed of that drive effectively diminishes. If one day your drive has 200 GB space remaining and the next day that same drive is inexplicably down to 20 GB, the next logical step would be to scan for malware.

Network Utilization

Some malware types—in particular, spyware—can be used to obtain information about you or your computer and then forward it back “home” to a hacker or other malicious user. Whether this information is used for identity theft, or is simply reconnaissance for a future attack, there is still some amount of network activity required for that data to reach its destination. It can be difficult to detect in a home environment but it is still important to know the signs; these include unfamiliar networking services or connections to unknown hosts, and an unusually high level of network activity (in particular when you’re not browsing the internet and have few or no networked devices talking back and forth).

Browser Redirection

After installing a “free” program or file of dubious origin, you may find that your web browser’s home page has been changed, or perhaps there are unusual toolbars you didn’t previously have installed; both cases are cause for concern and should be investigated. Spyware and adware often contain browser hijacking components, create pop-up ads, and cause other inconveniences when surfing the Web. While it is common for legitimate sites to try to bundle you with unwanted programs, there will (should) always be an opt-out, simply requiring you de-select extra software prior to confirming the download and/or installation. Less reputable sites may not give you this option—this is of course a red flag, but it comes too late as you’ll have already exposed your system to the threat.

Crashing or Locking Up

When a PC frequently crashes or freezes, it could mean a few things, imminent hardware failure being among them. While a corrupted hard disk or a bad memory module is definitely urgent, the threat of malware requires greater immediacy in order to ensure your personal privacy and critical data are protected; therefore it is recommended to scan the system for intrusion upon recovery from a crash. (Provided that the system is stable enough to do so.)

Addressing the threat of Malware

To supplement whatever your preferred antivirus/anti-malware is capable of detecting (which isn’t everything), it is recommended to run more than one antivirus application on a regular basis; by conducting in-depth scans using multiple different detection engines you can have some certainty that your computer is safe. Additionally, some varieties of malware (spyware, frequently) simply necessitate having specialized tools available to combat them. Lastly, since many advanced malware programs can obfuscate themselves, detection methods also need to take that into consideration; one such example is Avast’s “boot-time scan” feature, which scans the computer prior to booting up the operating system—thus negating the malware’s ability to hide itself within the file system.
A long list of recommendations is sure to follow in a future post. But for now, here are some answers to the specific threats mentioned in this article:
Avast (antivirus)
Malwarebytes (antivirus)
Webroot (antivirus)
Hitman Pro (“second opinion” antivirus)
Spybot Search and Destroy (anti-spyware)
TDSSKiller (rootkit remover)

Understanding and avoiding future threats

Detection, prevention, and remediation are critical to keeping your computer safe from malware; but, an even better approach is to avoid infection in the first place. Certain “high risk” activities amplify your chances for exposure almost exponentially. This includes P2P sharing, visiting adult websites, and downloading software through unscrupulous repositories. Less reputable repository sites tack on additional programs, usually spyware or adware, without your explicit permission. (You can get frequently around this by paying attention during the installation process, and deselecting any add-ons).

Phishing and questionable links/files

Another major threat comes via email. While phishing emails certainly aren’t new, the sheer volume and complexity of these messages is increasing dramatically. The average user will most likely be fooled at some point and click on something they shouldn’t have. This frequently comes in the form of a malicious link that delivers its payload via cross-site scripting. Another method which is less common nowadays due to spam filtering techniques is to send a specially crafted file which spoofs a .pdf, .zip, or other type of benign file extension, but actually contains a malware package which installs itself once executed by the user. Whatever the mechanism, the goal is to compromise the victim’s system by infecting it with malware.

One last thing to be very conscious of is that attackers can spoof addresses from your contact list in order to make the phishing message seem more trustworthy; for all of these reasons, here are some good practices to follow:
• Assume that all unsolicited file attachments are phishing attempts and delete them, regardless of type.
• Verify the legitimacy of suspicious links you receive from known contacts before clicking on them. Same holds true with URLs sent to you via messaging apps and SMS/MMS.
• If the subject line doesn’t match the body, or if there is no message body, consider it suspicious.
• Check the email header information to verify that the “from” address matches the actual sender’s email address. This can be difficult with advertisement emails as they often use aliases.
• When in doubt, delete the message.
• Use free services such as to analyze even “safe” URLs, for additional reassurance.

The Takeaway

PCs tend to slow down and generally perform less optimally over time. However, excessive slowness can be a sign of malware or other malicious activity affecting your system. Any single anti-malware solution is insufficient to address all of the various threats on the landscape; instead of relying on just one favorite become accustomed to using multiple virus detection engines to minimize risks. Safe browsing practices and an understanding of phishing campaigns are two of the keys to staying relatively safe online.


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