Is there a kanji for "hacker"? As I understand it, most foreign words in Japanese are written in Katakana. However, I am curious as to whether in contemporary written Japanese, hacker is written as a literal adaptation of the western word, or whether a idiomatically Japanese character/concept is substituted in its place. For the purposes of this discussion, what I mean by hacker is "Person who attempts to subvert the security of digital systems" rather than the wider meaning of the term. Is this even a concept in contemporary Japanese outside of its status as foreign word?

**** is widely recognized by the general population in the _narrow_ sense OP indicated. But if you use this in, say, Japanese Stack Overflow, it will soon be corrected. "Hey, don't use in that way! They're not criminals!"

**** specifically refers to the evil ones, and is preferred by IT professionals.

That said, both and are still a bit slangy terms in Japanese. Although newspapers seem to use freely recently, official government documents still avoid using them. For example, Information-technology Promotion Agency, which is a semi-official organization, does not use /, and uses other lengthy replacements like **……** in its security guidelines.

I don't know why you need a kanji version, but hope this helps.