But... do it right. And, like everything else in your resume, only do it if it will be beneficial.
It all depends on how you pitch it. For instance, don't say, "I wrote an aimbot". (Unless you expect the hiring staff to not comprehend an aimbot, or at least the controversial aspect of that.) Look at how much negative responses showed up on this Stack Exchange question. You want to avoid that.
Instead: You could claim that you wrote a program that assists people with a handicap (e.g., being human and inferior to machines) so that they could use a mouse more effectively. People using this popular program have been more successful... etc. etc.
Okay, so I confess: I was just having a bit of fun with that last paragraph. Really, don't actually say that on your resume. The problem with that paragraph is that it seems too misleading (suggesting being helpful with disabilities). Being detected as an intentional misleader will not help your cause. However, speaking seriously again, there are ways to pitch things by using ethical, moral, honest descriptions that will help your cause.
As a person who had done some hiring and assisted with some more hiring, I find that a lot of resumes fail to describe activity in a useful way. I'm talking about spin, here. I'm not talking about dishonesty. Heaven forbid (literally).
As an example, I'm involved with IT. A lot of young people want to get into the field, with little background in the computer field. I'd like to see someone who demonstrates an understanding of business goals, including the goals of my business.
- If you worked at a fast food restaurant, I don't want to see: "Made hamburgers faster than everyone else." I'm not in the hamburger business. What do I care?
- I want to see: "Reduced required time for product assembly, resulting in product being hand-delivered more quickly and customer satisfaction going up."
If you worked at a car wash, I don't want to see: "Rinsed cars with fewer errors per week than co-workers."
I want to see: Cleaned equipment with superior levels of adhering to company standards
I'm not trying to promote using unfamiliar vocabulary to impress people, nor am I suggesting that you try try to twist facts in a way that is only slightly misleading. If you see what I wrote, it is an absolutely honest way of describing what happened. However, it describes things in a way that demonstrates that when my boss tells me to make hamburgers, I don't just get so focused on my experience that I describe things from my perspective. Instead, I acknowledge the company's perspective by describing things in a way that might sound a bit more useful to the company I want to work for.
Does the company I want to work for have customers? Do they care about quality? Do they care about working efficiently (faster, or with fewer resources)? Describe how your activity helped to achieve some good goals that will be commonly appreciated.
If you can, describe your efforts in a way that applies to the company you want to work for. If that doesn't seem possible (because the company you want to work for is a very different type of company), at least show that you can explain things in a way that sounds appealing to a manager. At least then I will know that you can understand a manager's perspective, and you'll be head and shoulders above others who don't seem to understand what a manager would want to see.
For instance, I've programmed and currently running one of the most elusive and notorious aimbots on a quite popular virtual combat simulation platform - about 10,000 lines of C++ and counting
"I successfully created and released a working program that enhances the experience of other popular software. My project includes thousands of lines of computer code, and continues to work well despite evolving challenges that result from how the software is used on various networks."
I also played with a few websites of the "show your achievements" nature - never did any damage, just sort of tricked them with some minor scripting into ranking my (admittedly fictitious) achievements #1 worldwide.
No, don't say that. What you did may be a crime. Even if it wasn't, it sounds like something that many people will think was criminal. Don't say that.
"I identified the limits of what can be supported by some online databases, and through my own private exploration I became familiar with some identified real-world vulnerabilities on actual publicly deployed websites."
As a general rule, you should be prepared to discuss anything on your resume during your interview. Manipulating public competition, in the ways you describe, is not generally viewed as admirable. Before considering your resume to be finalized, put some thought into what can be safe to discuss, and what might not be. If something isn't beneficial to you to discuss, determine a sensible reason why you might want to limit such a discussion. ("Because of concerns of potential misuse, I'm limiting some details from widespread public disclosure. However, if I do get hired, I will be able to verify every statement I provided.")