An information stealer is malware designed to collect credentials, sessions, and other valuable data from an infected device. In practice, it targets browsers, email clients, wallet software, and stored tokens so attackers can reuse trusted access elsewhere.
Expanded Definition
An information stealer is malware built to harvest credentials, session cookies, browser autofill data, email access, wallet files, and stored tokens from an endpoint, then exfiltrate that data for reuse in follow-on intrusion. In NHI security, the impact is not limited to stolen passwords. A stealer often captures the artifacts that make a service account, API key, or authenticated browser session immediately reusable by an attacker.
Usage in the industry is still evolving because some teams treat stealer output as ordinary endpoint compromise, while others classify it as a direct identity exposure event. NHI Management Group treats it as both: a malware infection and an identity compromise vector that can bypass MFA when session material is stolen instead of a password. That is why identity monitoring, secret hygiene, and endpoint response must be coordinated with guidance from the NIST Cybersecurity Framework 2.0. The most common misapplication is assuming browser sign-out or password reset is sufficient, which occurs when stolen cookies, refresh tokens, or API keys remain valid after the endpoint is cleaned.
Examples and Use Cases
Implementing detection and response rigorously often introduces friction between user productivity and containment speed, requiring organisations to weigh rapid credential revocation against the business cost of interrupting legitimate sessions.
- A developer workstation is infected and the stealer exports browser-stored cloud console sessions, allowing an attacker to access CI/CD pipelines before the password is changed.
- An employee opens a malicious attachment, and the malware captures email tokens that remain usable even after MFA is enforced on the account.
- A finance team device is compromised and wallet software files are copied, creating immediate risk of fraudulent transfers and recovery challenges.
- A shared admin laptop leaks cached VPN and SaaS cookies, showing why identity artifacts on endpoints are high-value targets in the Ultimate Guide to NHIs.
- A service desk reset removes a password but not active tokens, so the attacker keeps access until the session layer is invalidated under NIST Cybersecurity Framework 2.0 recovery procedures.
Why It Matters in NHI Security
Information stealers matter because they convert an endpoint compromise into identity reuse at scale. For NHI programs, that means the attacker is often not trying to break authentication directly. Instead, they are stealing the already-trusted material that lets them impersonate a user, a developer, or an automated workload. This is especially dangerous where secrets are stored outside managed vaults, where sessions persist too long, or where service credentials are embedded in tools and scripts. NHI Management Group reports that 79% of organisations have experienced secrets leaks, and 77% of those incidents caused tangible damage, which shows how often stolen identity material leads to real operational loss.
Stealer-driven incidents also expose weak offboarding and rotation discipline. If a compromised endpoint had access to API keys, refresh tokens, or admin cookies, the organisation must revoke and reissue identity material quickly, not simply reimage the device. The same lesson applies to service accounts and automation identities that mirror human access patterns. The Ultimate Guide to NHIs shows how frequently secrets remain exposed after notification, which is why stealer incidents become a governance issue as much as a malware issue. Organisations typically encounter the full impact only after unusual logins, token replay, or cloud abuse appear, at which point information stealer response is operationally unavoidable to address.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 and OWASP Agentic AI Top 10 address the attack and risk surface, while NIST CSF 2.0, NIST Zero Trust (SP 800-207) and NIST SP 800-63 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-02 | Stealers expose secrets, tokens, and sessions, which this control targets directly. |
| NIST CSF 2.0 | PR.AC | Stealer infections become access-control failures when stolen identity artifacts remain valid. |
| NIST Zero Trust (SP 800-207) | Zero trust assumes stolen credentials alone should not grant enduring access. | |
| NIST SP 800-63 | Session theft undermines authenticator assurance even when passwords are unchanged. | |
| OWASP Agentic AI Top 10 | Agentic tools are exposed when stealer malware captures their delegated credentials or tokens. |
Limit session lifetime, monitor anomalous access, and revoke compromised credentials immediately.
Related resources from NHI Mgmt Group
- Who is accountable when an AI concierge gives guests incorrect or harmful information?
- Who is accountable when unauthorized use of personal information occurs?
- What do teams get wrong about least privilege for confidential information?
- Who is accountable when confidential information is exposed through poor handling?
