nisesaito ha zyouhourouei no genin da.

A natural reading is:

偽サイトは情報漏洩の原因だ。
にせサイト は じょうほうろうえい の げんいん だ。

Word by word:

• 偽サイト = にせサイト = fake site / fraudulent website
• 情報漏洩 = じょうほうろうえい = information leak / data leak
• 原因 = げんいん = cause
• だ = plain-form is

Note that サイト is a katakana loanword from English site.

は marks the topic of the sentence.

So 偽サイトは means something like:

• as for fake sites, ...
• fake sites are ...

The sentence is presenting 偽サイト as the thing being talked about, then saying something about it:

• 偽サイトは情報漏洩の原因だ。
• Fake sites are a cause of information leaks.

If you used が, the nuance would change. が tends to mark the grammatical subject more directly and can sound more specific or contrastive depending on context. For a general statement like this, は is very natural.

Here, の links two nouns:

• 情報漏洩 = information leakage
• 原因 = cause

So 情報漏洩の原因 means:

• the cause of information leakage
• a cause of data leaks

A very useful way to think about の is that it often works like:

• of
• or a noun-to-noun connector

In this sentence, it is not possession in the narrow English sense. It is just connecting the ideas:

• information leakage
  • cause
• cause of information leakage

Because 原因 is a noun, and Japanese often uses the copula だ to say that something is something.

So:

• 原因だ = is a cause

This is similar to other basic noun sentences:

• 学生だ = is a student
• 問題だ = is a problem
• 原因だ = is a cause

Japanese does not need a separate verb like cause here. It simply says that the topic is a cause.

だ is the plain form of the copula.
です is the polite form.

So:

• 偽サイトは情報漏洩の原因だ。 = plain / casual / dictionary-style
• 偽サイトは情報漏洩の原因です。 = polite

Both are grammatically correct. The choice depends on tone and context.

You often see だ in:

• written explanations
• headlines
• textbooks
• plain statements
• casual speech

You often use です in:

• polite conversation
• formal writing for learners
• presentations
• customer-facing language

偽サイト literally means fake site or fraudulent website.

Breakdown:

• 偽 = fake, false
• サイト = site, website

Depending on context, it can refer to:

• a fake login page
• an imitation shopping site
• a scam website
• a phishing website

In cybersecurity contexts, a more specific term you may also see is:

• フィッシングサイト = phishing site

So 偽サイト is understandable and natural, but sometimes フィッシングサイト is used when the meaning is specifically phishing.

It can easily mean fake websites in general.

Japanese often does not mark singular vs. plural as explicitly as English does. So 偽サイト can mean:

• a fake website
• fake websites
• fake-site activity as a category

The exact meaning depends on context.

In a general warning or educational statement, this sentence is usually understood as a general claim:

• Fake sites are a cause of information leaks.

If you wanted to make it clearly plural, you might say:

• 偽サイトは情報漏洩の原因の一つだ。
  = Fake sites are one cause of information leaks.

But even without explicit plural marking, the original sounds fine.

Japanese does not normally use articles like English a or the, and it usually does not require plural marking either.

So 偽サイト can mean:

• a fake site
• the fake site
• fake sites

And 原因 can mean:

• a cause
• the cause

You figure out the most natural English translation from context.

That is why one Japanese sentence can correspond to several English versions, such as:

• A fake site is a cause of information leakage.
• Fake sites are a cause of information leaks.
• Fake websites cause data leaks.

Japanese often puts the main statement at the end.

Literal structure:

• 偽サイトは = as for fake sites
• 情報漏洩の原因 = cause of information leakage
• だ = is

So the sentence is basically:

• As for fake sites, they are a cause of information leakage.

English usually goes more directly:

• Fake sites are a cause of information leakage.

Japanese commonly uses a topic-first, key-point-last structure. That is very normal.

Yes, 情報漏洩 is a compound noun.

It is made of:

• 情報 = information
• 漏洩 = leak, leakage, disclosure through leaking

So literally it is something like:

• information leakage
• data leak
• information disclosure by leakage

In IT, business, and security contexts, 情報漏洩 is a very common formal term.

Yes. They are the same word.

You may see:

• 漏洩
• 漏えい

The second version uses kana for part of the word, which sometimes appears in official or accessible writing.

Both are read ろうえい and mean leakage or disclosure by leaking.

So:

• 情報漏洩
• 情報漏えい

both mean information leakage / data leak.

No. Standard Japanese is usually written without spaces.

So the normal writing is:

偽サイトは情報漏洩の原因だ。

Spaces are sometimes added in learning materials to make the structure easier to see, but native Japanese writing normally does not use them this way.

Yes, absolutely.

Even though the Japanese literally says:

• Fake sites are a cause of information leakage

a more natural English translation in some contexts is:

• Fake sites cause data leaks.

That is because English often prefers a verb-based sentence, while Japanese is perfectly happy with a noun + copula structure like 原因だ.

So the literal grammar and the best natural translation are not always identical.