#1 Infostealers Versus Your Organization
Purpose
This article gives IT professionals a concise, non‑technical overview of infostealers, using real‑world data (anonymised) to illustrate the threat.
It is not a how‑to guide for attackers.
What Is an Infostealer?
An infostealer is a piece of malware that quietly runs on a victim’s machine and collects sensitive data – passwords, session tokens, bank details, etc.
Once collected, it sends the data to a remote attacker for exploitation (identity theft, fraud, ransomware extortion, etc.).
How Do They Operate?
| Phase | What They Do | Typical Indicators |
|---|---|---|
| Delivery | Phishing emails, malicious downloads, compromised websites. | Suspicious attachment names, unknown URLs. |
| Execution | Runs silently, sometimes masquerading as a legitimate process. | New process names, registry tweaks, scheduled tasks. |
| Harvesting | Scrapes web‑forms, browser stores, OS credential vaults. | Credentials appear in outbound traffic or in logs. |
| Exfiltration | Sends stolen data to a command‑and‑control (C2) server. | Unusual outbound HTTPS or DNS requests. |
| Lateral Movement | Uses stolen credentials to access other systems. | Unexpected logins from new devices. |
Real‑World Example (Anonymised)
Below is a sanitised excerpt from a recent internal CTI export.
Notice how the data is grouped by user, credential type, and source of the leak.
| Imported at | Indicator of ID | Credential (obfuscated) | Source |
|---|---|---|---|
| 9/17/2025, 5:08 PM | user@example.com | Jd**id&2024 | url_login_pass |
| 9/16/2025, 9:17 AM | user2@example.com | Moo**532 | stealer_logs |
| 9/13/2025, 12:14 AM | user3@example.com | 1**88dd30 | url_login_pass |
| 9/09/2025, 7:25 PM | user4@example.com | Ha**i@3566 | url_login_pass |
| 9/09/2025, 2:43 AM | user5@example.com | Sua.mae* | stealer_logs |
| 9/04/2025, 7:32 AM | user6@example.com | TopR**eV$t8*IOxb | url_login_pass |
| 8/29/2025, 9:43 AM | user7@example.com | J**esclef* | combolists |
| 8/28/2025, 12:01 AM | user8@example.com | $T**JaSnE*9H | url_login_pass |
| 7/29/2025, 4:43 AM | user9@example.com | Dest**77*@5 | url_login_pass |
| … | … | … | … |
Key Take‑aways
- High volume of simple, guessable passwords – attackers prefer weak, common credentials.
- Multiple sources:
url_login_pass(captured on web login),stealer_logs(direct extraction),combolists(pre‑compiled credential lists). - Rapid recurrence: Same user accounts appear over many days – indicates automated credential‑stealing.
Detection & Response Checklist
| Step | Action | Tool/Technique |
|---|---|---|
| 1. Endpoint Protection | Run full malware scan, monitor for unknown processes. | EDR (CrowdStrike, SentinelOne) |
| 2. Network Monitoring | Inspect outbound HTTPS/DNS for known malicious domains. | Zeek, Suricata, SIEM |
| 3. Credential Auditing | Check authentication logs for anomalous events. | MFA logs, IAM dashboards |
| 4. Isolation | Quarantine infected machine, block outbound traffic. | EDR isolation, firewall |
| 5. Credential Reset | Force password change for affected accounts. | Password policy, MFA |
| 6. Patch & Harden | Apply OS/app patches, enforce least privilege. | WSUS, configuration baselines |
Mitigation Strategies
| Layer | Recommendation |
|---|---|
| Prevent | • Deploy MFA everywhere. • Enforce password complexity and rotation. • Keep all software up‑to‑date. • Use reputable anti‑malware. |
| Detect | • Continuous endpoint and network monitoring. • Update IOC feeds regularly. • Run regular phishing simulations. |
| Respond | • Have a documented playbook for credential‑theft incidents. • Automate isolation and credential reset. • Keep immutable backups. |
Final Thoughts
Infostealers are a low‑hanging fruit for attackers.
The data above shows that even well‑protected environments can fall prey if basic controls are not in place.
Your next steps:
As an individual or organization, keeping track of breaches and dark web leaks goes a long way for addressing leaks and patching security before threat actors use information from said leaks to attack you and your systems.
We offer realtime dark web monitoring which allows you to know immediately when your credentials show up on the darkweb and provide you with actionable insights on how to react accordingly. This ensures all year round protection against threat exposure.
Stay vigilant – the next attack could target a user that appears safe.