In this type of attack, a hacker or spammer will use a Bot to probe your system using HTTP set up with a non-standard, invalid or corrupt user agent ( a user agent is part of the information a website receives from a visitor about who the visitor is ). These type of attacks account for attacks that conduct click fraud, web-scraping, brute force attacks, data mining, account hijacking, site scanning among others.
It is not unusual for a third of the traffic a website receives to be classed in the ‘Bad Bot' category which suggests that this type of activity is always ongoing; this is not surprising considering the automated approach applied to these malicious crawlers.
It is possible to take action to prevent crawler activity on your site, especially if your website is consuming a lot of resources to deal with this type of visitor.
Fortunately, the origin of bad bots emanates from a small group of countries so if you have a localised business you could consider using Geo-location to prevent them from getting anywhere near your website.
Although one of the best things about the internet is sharing of information letting anyone reference images and other resources directly from your website may not be such a great idea.
Hot-linking, although may seem innocuous, can be quite harmful. Although you may be prepared to share your content across the internet with others, when someone targets you on with hot-linking, they will be using your bandwidth. If the attack is malicious, then taken to the extreme it could consume all of your bandwidth and this could render your website unusable or even take it offline. If your ISP operates in such a way you may also be liable for excessive bandwidth charges.
When web builders use this method without first gaining authorisation to use the resources it can be considered as a bad practice and as such these type of hot linkers are probably unaware of the issues they may be causing for the target website or for themselves. However, in the cases where a hacker uses this method it can, unfortunately, be a very effective website takedown method.
The problem is simple to resolve and a competent practitioner can use one of many methods, such as modification of the .htaccess file on their website, to alleviate this issue.
Distributed Denial of Service (DDoS)
This is one of the worst types of attacks to be on the receiving end of. Here an attacker will set up an ‘army' of virus or trojan-infected computers that will all target your website with a view to bringing it down, or as its name implies to create a denial of service.
DDoS is a highly prevalent threat with internet monitors seeing 2000 such attacks daily. Take a look at the DDoS Attack Map how prevalent this is.
The army of computers will be created by the attacker infecting PC's and other computers in normal daily use through emails, social media and other pervasive methods of distribution. The advent of virtual machine technology has further exacerbated this as thousands of computers can be created by an attacker in one of the cloud computing engines at really low cost.
These infected computers then act under the control of a central control computer as a giant Bot working in collaboration to attack the target website.
What is worse is that they can be bought online, starting at really low prices, and when targeted at a small company website can quickly overpower it. It is not uncommon for such an attack to cost as little as $150 for keeping a website out of action for up to a week.
Dealing with this type of attack is non-trivial and requires pre-planning and resources in place to be able to detect such an attack but once under attack due to the sheer volume and intensity of such events, you may not be able to survive without an outage.
Injection threats essentially exploit bad programming practices that have managed to become implemented on a website.
The most commonly known injection type is the ‘SQL Injection' which is where a hacker obtains access to an underlying database on the website. This is done by crafting an SQL command and injecting it into an on-page form or another data collection point on the website.
The list goes on...
These are some of the tactics used by cyber criminals and web hackers to disrupt websites. Even if you do have defences against these types of attacks the technology is always evolving so you must never rest on the good work you have already put in.