An infostealer is malware that collects sensitive data such as credentials, browser sessions, tokens, and autofill information from a device. A keylogger focuses on recording keystrokes, sometimes as one component of broader theft. Defenders should watch for browser credential theft, token exfiltration, suspicious input hooks, and unexpected data sent from endpoints.
How Infostealers and Keyloggers Differ in What They Capture
An infostealer is built to harvest high-value data from a device, so the output is usually broader than just typed text. That often includes saved browser credentials, session cookies, tokens, autofill data, and other artifacts that let an attacker bypass normal login steps. A keylogger is narrower by design, recording keystrokes as they are entered, which may reveal passwords or messages but not the wider credential set an infostealer targets.
The practical difference is that infostealers are usually judged by the access they can enable after the infection, while keyloggers are judged by the input they can observe. In real incidents, the same malware family can combine both behaviours, but defenders should not assume that a keyboard capture tool automatically has browser vault access, or that a stealer necessarily needs keystroke interception to be effective.
Because infostealers often extract session material, browser stores, and tokens, they can create immediate account takeover risk even when a password is later changed. Keyloggers can still be damaging, but the compromise path is often more dependent on what the user typed and whether the attacker can reuse those keystrokes before the secret is rotated.
What Defenders Should Look For on Endpoints and in Browser Data
Detection should follow the data the malware is trying to take. For infostealers, that means watching for browser credential theft, token exfiltration, unusual reads of profile and cookie stores, and suspicious outbound transfers from endpoints shortly after execution. For keyloggers, the stronger signals are input hooks, keyboard or accessibility API abuse, and suspicious persistence on the host.
The difference matters because a host can be compromised without showing obvious password theft. If browser session theft is the concern, the investigation has to include active sessions, synced browser profiles, and API tokens, not just password resets. If the concern is keystroke capture, focus more on how the malware attaches to input paths and whether the device was exposed long enough to capture valuable credentials.
Many operators also use stealthy loaders or droppers to stage either behaviour, so endpoint telemetry should be reviewed for process injection, unusual parent-child process chains, and archive or script execution preceding the theft activity. A narrow keylogger may leave less network noise than a stealer that synchronises harvested data to external infrastructure.
Why the Difference Changes Response and Containment
Response actions differ because the likely exposure differs. When an infostealer is confirmed or strongly suspected, rotating passwords alone is not enough if tokens, cookies, SSH keys, or cloud sessions may have been copied. When a keylogger is the only confirmed behaviour, the immediate question is whether the attacker captured credentials that are still valid, and whether the keyboard capture period overlapped with privileged activity or password entry.
That distinction also changes scope. Infostealer investigations often need browser and session-level containment across multiple services, while keylogger investigations may stay more endpoint-centred unless the captured keystrokes already enabled lateral movement. In both cases, the safest assumption is that whatever the malware could observe may already be in the attacker’s hands.
Risk and Threat Considerations
Infostealers are especially dangerous because they can steal material that remains useful after the original infection is removed. Session cookies, refresh tokens, and saved credentials can turn one endpoint compromise into broad account access, especially when MFA is bypassed through already-authenticated sessions. Keyloggers are usually narrower, but they become high risk when the victim types privileged credentials or one-time access data.
Failure mechanism: Infostealers abuse local browser stores, session caches, and token material, while keyloggers abuse the trusted keyboard input path. In both cases, the attacker benefits when the secret is captured before rotation or before the session is invalidated.
Impact: The result can be account takeover, replay of active sessions, theft of cloud or SaaS access, and follow-on misuse of any systems reachable from the stolen identity material. The more privileged the captured secret, the faster a local compromise becomes an enterprise incident.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK and OWASP Non-Human Identity Top 10 address the attack and risk surface, while NIST SP 800-53 Rev 5 sets the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| MITRE ATT&CK | T1056 — Input Capture | Covers keystroke capture and other input interception used by keyloggers. |
| T1003 — OS Credential Dumping | Infostealers often target locally stored credentials and authentication material. | |
| T1555 — Credentials from Password Stores | Infostealers frequently harvest browser-saved credentials and related secret stores. | |
| Recommendation — Map input-hook activity to T1056 and hunt for keyboard interception on affected endpoints. Look for credential access activity and restrict local access to stored secrets. Search for password-store access and rotate exposed credentials immediately. | ||
| OWASP Non-Human Identity Top 10 | NHI-02 — Secret Leakage | Infostealers steal credentials, tokens, cookies, and other reusable secret material. |
| NHI-07 — Long-Lived Secrets | Captured cookies and tokens remain useful when they are not short-lived or bound tightly. | |
| Recommendation — Inventory exposed secrets and revoke or rotate anything the stealer could have copied. Shorten secret lifetimes and invalidate reusable sessions after exposure. | ||
| NIST SP 800-53 Rev 5 | IA-5 — Authenticator Management | Responder actions often require rotation, revocation, and lifecycle control of exposed authenticators. |
| AC-2 — Account Management | Account containment after infostealer or keylogger exposure depends on disabling or resetting affected accounts. | |
| Recommendation — Rotate exposed authenticators and revoke affected sessions and tokens. Disable compromised accounts and review privileged access paths for reuse. | ||
Practitioner Guidance
What to verify: Confirm whether the compromise exposed only typed credentials or also browser sessions, autofill records, tokens, and other reusable authentication material. That tells you whether session revocation and token rotation are mandatory, or whether password reset may be sufficient for the first containment step.
Decision rule: If there is any sign of browser artifact theft, treat the event as a wider identity exposure, not a simple malware cleanup. If the evidence points only to keystroke capture, prioritise the accounts used on the affected endpoint and validate whether privileged credentials were entered during the exposure window.
Practitioner takeaway: The key distinction is reuse, not just observation, infostealers often steal material that remains valid after infection, while keyloggers mainly capture what a user typed at a specific moment.
Related resources from NHI Mgmt Group
- Guide: Infostealer Threat Guide
- What is the difference between prompt injection risk and identity abuse in agents?
- What is the difference between SAST and DAST for security teams?
- What is the difference between credential theft and file theft in a macOS infostealer campaign?
- What is the difference between loader malware and an infostealer in a phishing campaign?