Infostealers are purpose-built to remain undetected for as long as possible. The longer a victim is unaware of the infection, the longer the stolen credentials remain valuable. Once a breach is discovered, passwords are reset, tokens are revoked, and access is lost. That’s why infostealers operate quietly — it preserves the resale value of logs in the criminal marketplace. Delayed detection is not a side effect. It’s the business model.

Their behavior is short-lived and typically doesn’t rely on persistence — especially in early stages — and often happens outside of the organization’s security perimeter.

Most AV and EDR systems fail to catch them because:

• They execute briefly and in-memory — leaving no trace for behavioral analysis or sandboxing

• They don’t require persistence to be effective — though some establish footholds later via droppers, autostarts, or scheduled tasks

• They operate outside managed environments — many infections occur on personal, BYOD, or unmanaged devices that aren’t covered by endpoint protection

Even advanced EDR tools struggle to detect infostealers when the device is not enrolled in management or when telemetry is unavailable.

Many stealers use techniques documented in MITRE ATT&CK T1555.003 — extracting credentials from local storage or password managers without triggering alerts. Because most infections happen on endpoints the organization doesn’t control, traditional security tools can’t see them — and never raise an alert.