How Are Passwords Stolen? From Infostealer Malware to Cloud Misconfigurations

Passwords rarely “just leak” by accident — they’re stolen through a well-honed playbook that blends malware, social engineering, and infrastructure mistakes. This article unpacks the most common attack vectors, why they work, and how to defend against them.

1. Infostealer Malware: The Silent Vacuum Cleaner

Infostealers are lightweight programs designed to grab anything of value from an infected device — especially credentials.

• Most variants bundle a keylogger, form-grabber, clipboard hijacker, and even screen-capture capabilities, giving attackers multiple ways to lift passwords before they’re encrypted or stored1.
• Stealer malware is now one of the fastest-growing tools in the cyber-crime arsenal, sold “as-a-service” on underground markets2.
• Popular families such as RedLine, Vidar, Raccoon, and Lumma target browser-saved passwords, cookies, crypto wallets, and sometimes MFA tokens23.

How it happens

1. Infection (phishing, malicious ads, cracked software).
2. Local harvest of credentials, cookies, and system data.
3. Covert exfiltration to a command-and-control server.
4. Immediate monetization via Initial Access Brokers or credential-stuffing bots.

Defense tips – Keep OS and browsers patched, run reputable endpoint protection, and block known stealer C2 domains. – Disable browser password storage; use a dedicated password manager with breach-monitoring features. – Educate staff on the dangers of downloading “free” software and game mods.

2. Phishing & Social Engineering: Low-Cost, High-Yield

Phishing emails, texts, and voice calls remain the easiest way to trick humans into handing over passwords4. Attackers spoof login pages, intercept credentials in real time, and often bypass basic two-factor methods such as SMS.

Defense tips – Deploy email filters that block look-alike domains and scan links. – Train users to verify URLs and report suspicious messages. – Enforce phishing-resistant MFA (FIDO2, hardware keys) on critical accounts.

3. Brute-Force & Dictionary Attacks

Automated tools systematically guess passwords until they succeed.

• Brute-force attacks iterate through all possible combinations, while dictionary attacks try the most common password phrases first4.

Weak or reused passwords collapse quickly under sustained guessing.

Defense tips – Require long passphrases (≥ 16 characters) and block the top 1,000 compromised passwords at sign-up. – Rate-limit login attempts and use adaptive risk scoring.

4. Password Reuse & Credential Stuffing

More than half of users still recycle passwords across sites4. Once one service is breached, attackers feed the email-password combo into bots that bombard other services — a practice known as credential stuffing.

Defense tips – Mandate unique passwords per site via a manager. – Monitor for leaked hashes and force resets when hits appear.

5. Man-in-the-Middle (MitM) & Rogue Wi-Fi

Attackers position themselves between you and a legitimate service to intercept credentials in transit.

• Spoofed public hotspots at airports and cafés are common staging grounds4.

Defense tips – Always verify the network name and use a VPN on untrusted Wi-Fi. – Enforce HTTPS and HSTS on all web properties.

6. Cloud Misconfigurations: Breaches at Platform Scale

Even perfect user hygiene can’t compensate for a server set to “public.”

• Misconfigured cloud buckets, over-permissive IAM roles, or disabled logging have fueled some of the largest data spills on record5.
• The 2019 Capital One breach (≈ 100 million customers) stemmed from an exposed web-application firewall in AWS5.
• A 2021 Microsoft Power Apps exposure left 38 million records publicly accessible due to default settings that were not secured5.

Once attackers download these data troves, passwords (hashed or plaintext) are fed straight into brute-force or credential-stuffing pipelines.

Defense tips – Enforce the principle of least privilege in IAM roles. – Run automated cloud-configuration scanners and remediate “public” flags immediately. – Encrypt sensitive data at rest and in transit; enable detailed logging for forensic visibility.

7. Unsafe Sharing & Shoulder-Surfing

• Texting or emailing passwords exposes them to interception and future account compromise4.
• Physical spying — literally looking over a person’s shoulder or photographing sticky notes — still works, even in the era of passkeys4.

Defense tips – Use secure, audited sharing features built into password managers. – Adopt passkeys or hardware tokens where feasible to eliminate typed secrets.

A Layered Defense Strategy

Key Takeaways

1. Infostealer malware now rivals phishing as the top source of stolen passwords, thanks to Malware-as-a-Service scale.
2. Cloud misconfigurations can leak millions of passwords in one mis-clicked permission.
3. Reuse remains the attacker’s best friend — once breached, a password can unlock many doors.
4. A defense-in-depth approach that combines user training, strong authentication, and hardened infrastructure is no longer optional.

Staying ahead of password theft means assuming compromise is inevitable and layering protections accordingly. Rotate secrets, enable MFA everywhere, and audit your cloud just as diligently as you patch endpoints — attackers certainly will.