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Cybercriminals can make malicious activity harder to spot by disguising it as ordinary system administration, using legitimate accounts, altering code so its signature changes, or hiding communications inside allowed network protocols. These patterns do not make an intrusion invisible; they make detection depend more on context, logging, and behavioral analysis than on spotting an unfamiliar tool or file.
What evasion means in cybersecurity
Defense evasion is a broad label for behavior intended to make malicious activity less visible or harder to identify. It is not one technique, and the examples below are not a complete catalogue of methods used by cybercriminals. The common thread is concealment: activity is made to resemble something a system or its defenders already expect.
A useful starting point is to ask not only “What tool or file is this?” but also “Who used it, on which system, at what time, and in what sequence of actions?” Legitimate software, accounts, and protocols can all be used in suspicious ways.
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Living off the land: using tools already in the environment
Living off the land (LOTL) means abusing native tools and processes already available in an environment. Because administrators also use those tools, the activity can look like routine maintenance rather than an intrusion. It may also lack the conventional indicators associated with a newly installed malicious program.
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A March 2025 joint guide from CISA, NSA, FBI, and partner agencies addresses LOTL across on-premises, cloud, and hybrid environments, including Windows, Linux, and macOS. Its emphasis is on mitigation, detection, and threat hunting—not on treating any single operating system or platform as uniquely exposed. Read the joint CISA and partner guidance on identifying and mitigating LOTL.
Why it can work
Security tools may see familiar administrative activity, while default logging may not capture enough detail to establish whether that activity was expected. A tool’s legitimate purpose does not prove that a particular use is legitimate.
What defenders can do
- Maintain baselines for expected administrative behavior and investigate meaningful deviations in users, systems, timing, and activity sequences.
- Improve visibility into relevant activity so investigators can reconstruct what happened rather than relying on a tool name alone.
- Hunt for unusual behavior in context, including activity by tools that are common in normal operations.
Software packing: changing how code appears
Packing compresses or encrypts an executable and changes its file signature in an attempt to evade signature-based detection. CISA’s ATT&CK technique page describes this method as Software Packing (T1027.002). A changed signature can weaken a detection approach that depends mainly on matching known file patterns; it does not establish that the file is safe or that other detection methods will fail. See CISA’s Software Packing technique entry.
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What defenders can do
- Do not treat a familiar or unfamiliar signature as the sole basis for deciding whether activity is malicious.
- Use file evidence alongside behavior and environmental context, and include broader detection and hunting in the response.
Valid and default accounts: making access look authorized
An attacker using a legitimate account may appear to be an authorized user, particularly when the account is built in or preset. CISA’s Default Accounts (T1078.001) entry describes use of such accounts across several adversary goals, including defense evasion. It also notes that stolen credentials can enable remote access through legitimate services. The technique page defines and categorizes behavior; it does not provide a product-specific control prescription. See CISA’s Default Accounts technique entry.
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What defenders can do
- Review account use in context, paying attention to whether the account, access path, and activity fit the role and system involved.
- Include remote access through legitimate services in identity monitoring rather than assuming that a valid login is benign.
Protocol tunneling: hiding communications in allowed traffic
Protocol tunneling wraps one protocol inside another. This can help communications blend with traffic an organization already permits, avoid some detection or filtering, or provide access to systems that would otherwise be unreachable. A common or encrypted protocol is therefore not automatically benign: its use still needs to make sense for the source, destination, and surrounding activity. See CISA’s Protocol Tunneling technique entry.
What defenders can do
- Include network behavior in detection and hunting, not just endpoint files and processes.
- Review traffic and filtering in context, looking for connections or patterns that do not fit expected system and user behavior.
What the 2023 PRC-actor advisory illustrates—and what it does not
In a May 24, 2023 announcement, CISA and partners summarized an advisory about a PRC state-sponsored actor using built-in network administration tools. The announcement says that this activity blended into routine Windows operations, limited what default logging captured, and avoided some EDR products. This is an attributed example involving a specific actor; it is not evidence that every EDR product always fails.
The example shows why visibility and context matter: recognizing a familiar administration tool is not enough if defenders cannot determine whether its use was expected or see the activity around it. Read CISA and partners’ announcement of the advisory.
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These technique families call for complementary defensive views. They are not a product ranking, and the cited sources do not establish that any one control is sufficient on its own.
| Defensive view | Question it helps answer | Why it matters |
|---|---|---|
| Visibility and logging | Can investigators see enough activity to reconstruct what occurred? | LOTL activity can be difficult to distinguish when logging captures too little detail. |
| Behavioral context and baselines | Does this action fit the user, system, time, and surrounding sequence? | Familiar tools and processes can be used in unexpected ways. |
| Identity and account oversight | Does this account’s use fit its role and expected access? | Valid credentials and built-in accounts can make malicious access appear legitimate. |
| Network monitoring and filtering | Does this communication make sense for the systems and services involved? | Tunneled traffic may use protocols that are already permitted. |
CISA’s guidance on MITRE ATT&CK mapping describes using ATT&CK to organize detections, hunt for threats, assess tool capabilities, and validate mitigations. Mapping observed behaviors to a shared technique framework can help teams identify what they can detect and where visibility or coverage needs attention; it is not a measure of how frequently a technique occurs. Read CISA’s best practices for MITRE ATT&CK mapping.
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