Fake CAPTCHA Trick Tied to Berlin Gov Data Leak

How the Attack Worked

According to reporting reviewed by Germany's Federal Office for Information Security (BSI), attackers compromised legitimate websites and inserted fake CAPTCHA verification pages. Instead of the usual click-to-verify checkbox, these fake pages instructed visitors to manually copy and run a command on their own computer to "complete verification." That single action gave attackers a foothold, enabling both data theft and, in some cases, ransomware deployment.

This technique matters because it shifts the attack from a technical exploit to a social engineering trick. The malicious code never has to bypass browser security controls because the victim runs it themselves, believing they are completing a routine step.

Why It Succeeded

CAPTCHA prompts are so common that most users no longer question them. The fake page exploited that familiarity, adding one small but critical deviation from normal since users are asked to open a command window or paste text rather than simply click a box. Because the sites involved were already compromised, the prompts appeared in a context users trusted, making the unusual instruction seem like a plausible extra step rather than an obvious red flag.

BSI also noted that this campaign, alongside the separate Berlin government data release, involved both theft and encryption in the same operation. Combining data theft with ransomware increases pressure on victims, since attackers can threaten to publish stolen data even if backups allow recovery from encryption.

What to Watch For

• A CAPTCHA page asking you to run commands is not normal behavior for a verification step
• Instructions that require copying or pasting text into a terminal or run dialog, rather than clicking a checkbox
• Verification prompts appearing on a site that never asked for them before
• Login credentials appearing in leaked data dumps, even without confirmation of which systems they unlock

Building Resistance

Organizations across government, education, and healthcare should treat this pattern as a training priority for all staff, not just IT teams. Practical steps include:

• Teaching employees to stop and report any prompt asking them to run commands, regardless of how official the page looks
• Building incident response workflows that assume ransomware incidents may include data theft, prioritizing rapid containment and notification
• Resetting passwords and reviewing access quickly whenever credentials may have been exposed, even before confirming which systems are affected
• Reinforcing that legitimate CAPTCHA checks never require manually executing code

The Berlin case shows how a straightforward social engineering trick, paired with the possibility of stolen credentials being reused elsewhere, can create risk well beyond the original target.

What is the fake CAPTCHA attack described in the Berlin case?

Attackers compromised websites and displayed fake CAPTCHA verification pages that instructed visitors to manually copy and run malicious commands on their own computers, enabling data theft and ransomware deployment.

What data was exposed in the Berlin government leak?

Hackers published stolen data from two Berlin ministries, including login credentials and potentially personal information such as names, addresses, bank details, emails, phone numbers, and documents belonging to public employees and possibly residents.

Why do ransomware groups combine data theft with encryption?

Germany's BSI reported that attackers in this campaign attempted both to steal data and install ransomware, using the threat of publishing stolen information as additional pressure on victims.

How can employees spot a fake CAPTCHA scam?

Any CAPTCHA or verification prompt that asks a user to copy and paste or manually run a command is abnormal, since standard CAPTCHAs only require a click, and such requests should be reported to IT or security immediately.