What is a computer worm ?

Definition:-A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. Often, it uses a computer network to spread itself, relying on security failures on the target computer to access it.

or,

A computer worm is a type of malware that spreads copies of itself from computer to computer. A worm can replicate itself without any human interaction, and it does not need to attach itself to a software program in order to cause damage.

Note:A computer worm is not to be confused with WORM (write once, read many).

Types of Computer Worms

Different types of Computer Worms are:

Email Worms

Spreading goes via infected email messages. Any form of attachment or link in an email may contain a link to an infected website. In the first case activation starts when the user clicks on the attachment while in the second case the activation starts when clicking the link in the email.

Known methods to spread are:
- MS Outlook services
- Direct connection to SMTP servers using their own SMTP API
- Windows MAPI functions

This type of worms is known to harvest an infected computer for email addresses from different sources.
- Windows Address Book database [WAB]
- MS Outlook address book
- Files with appropriate extensions will be scanned for email like strings

Be aware that during spreading some worms construct new sender addresses based on possible names combined with common domain names. So, the sender address in the email doesn't need to be the originator of the email.

Instant Message and Chat Room Worms

The spreading used is via instant messaging applications by sending links to infected websites to everyone on the local contact list. The only difference between these and email worms is the way chosen to send the links.

Internet Worms

Nasty ones. These ones will scan all available network resources using local operating system services and/or scan the Internet for vulnerable machines. Attempt will be made to connect to these machines and gain full access to them.

Another way is that the worms scan the Internet for machines still open for exploitation i.e. not patched. Data packets or requests will be send which install the worm or a worm downloader. If succeeded the worm will execute and there it goes again!

IRC Worms

Chat channels are the main target and the same infection/spreading method is used as above - sending infected files or links to infected websites. Infected file sending is less effective as the recipient needs to confirm receipt, save the file and open it before infection will take place.

File-sharing Networks Worms

Copies itself into a shared folder, most likely located on the local machine. The worm will place a copy of itself in a shared folder under a harmless name. Now the worm is ready for download via the P2P network and spreading of the infected file will continue.

History of computer worms

Although the Morris worm, released in 1988, is widely considered the first computer worm, it actually is better characterized as the first worm to propagate widely in the wild, and on the then nascent internet.

The Morris worm was the work of Robert Tappan Morris Jr., a Cornell graduate student who was reportedly attempting to enumerate all the systems connected to the internet precursor network, ARPANET. Targeted at vulnerabilities in several different Unix programs, the Morris worm was capable of infecting a system more than once, making it difficult to eradicate completely before it produced a denial-of-service condition on the infected host. As many as 10% of the 60,000 systems then believed to be connected to ARPANET were affected by the worm.

One of the most damaging computer worms ever was the ILOVEYOU virus, malware that was propagated through several vectors, including email attachments that appeared to be text files, scripts run in IM chat sessions, and copies of the virus in executables renamed with the names of common system files.

ILOVEYOU primarily spread when targeted victims opened an email attachment, and the malware resent itself to all of the victim's contacts in Microsoft Outlook. Though, technically, this aspect of the worm required user interaction, the overall effect was that the virus spread during normal operation of desktop computers, and without the initial awareness of the victims. The malware reportedly affected as many as 45 million users on May 4, 2000, spreading so rapidly that some enterprises, including Ford Motor Company, were forced to shut down their email services.

Stuxnet: the most famous computer worm

In July 2010, the first computer worm used as a cyber weapon was discovered by two security researchers after a long string of incidents in Iran. Dubbed “Stuxnet,” this worm appeared to be much more complex than the worms researchers were used to seeing. This attracted the interest of high-profile security specialists around the world, including Liam O’Murchu and Eric Chien of the Security Technology and Response (STAR) team at Symantec. Their extensive research led them to conclude that the worm was being used to attack an Iranian power plant, with the ultimate goal of sabotaging nuclear weapon production. Although the attack ultimately failed, this computer worm is still active on the threat landscape today.

How do computer worms work?

Worms can be transmitted via software vulnerabilities. Or computer worms could arrive as attachments in spam emails or instant messages (IMs). Once opened, these files could provide a link to a malicious website or automatically download the computer worm. Once it’s installed, the worm silently goes to work and infects the machine without the user’s knowledge.

Worms can modify and delete files, and they can even inject additional malicious software onto a computer. Sometimes a computer worm’s purpose is only to make copies of itself over and over — depleting system resources, such as hard drive space or bandwidth, by overloading a shared network. In addition to wreaking havoc on a computer’s resources, worms can also steal data, install a backdoor, and allow a hacker to gain control over a computer and its system settings.

How to help protect against computer worms ?

Computer worms are just one example of malicious software. To help protect your computer from worms and other online threats, take these steps.

Since software vulnerabilities are major infection vectors for computer worms, be sure your computer’s operating system and applications are up to date with the latest versions. Install these updates as soon as they’re available because updates often include patches for security flaws.
Phishing is another popular way for hackers to spread worms (and other types of malware). Always be extra cautious when opening unsolicited emails, especially those from unknown senders that contain attachments or dubious links.
Be sure to invest in a strong internet security software solution that can help block these threats. A good product should have anti-phishing technology as well as defenses against viruses, spyware, ransomware, and other online threats

if your computer has a worm

If you suspect your devices are infected with a computer worm, run a virus scan immediately. Even if the scan comes up negative, continue to be proactive by following these steps.

Keep an eye on your hard drive space. When worms repeatedly replicate themselves, they start to use up the free space on your computer.
Monitor speed and performance. Has your computer seemed a little sluggish lately? Are some of your programs crashing or not running properly? That could be a red flag that a worm is eating up your processing power.
Be on the lookout for missing or new files. One function of a computer worm is to delete and replace files on a computer.

How computer worms spread

A computer worm infection spreads without user interaction. All that is necessary is for the computer worm to become active on an infected system. Before widespread use of networks, computer worms were spread through infected storage media, such as floppy diskettes, which, when mounted on a system, would infect other storage devices connected to the victim system. USB drives are still a common vector for computer worms.

About Admin of the Blog:

Rajnish kumar is the CEO/founder of Tech Hindi Sagar .He is a Computer Science Engineer ,Web Designer,Web Developer and a Pro Blogger..Inspired to make things looks better.