Detect it by watching for curl or wget processes that fetch files from unusual domains, short-lived infrastructure, or raw IP addresses, then write executables or scripts to user-writable paths. Correlate downloads with subsequent execution and with command lines that suppress normal prompts or output. A download followed quickly by a new local binary is the key pattern.
What curl and wget activity looks suspicious on Windows
On Windows, the key signal is not the tool alone but the behavior around it. Legitimate admin activity usually pulls from known vendor or internal locations and places files in expected update or working paths. Suspicion rises when the download source is unfamiliar, the destination is a user-writable directory, and the command line is built to minimize prompts, logging, or visible output.
That makes the process tree important. A single network fetch is noisy but not always malicious. A fetch that is followed by script creation, a newly dropped executable, or an immediate child process launch is much more diagnostic, especially when the parent is curl, wget, PowerShell, cmd, or a scheduled task. The question is whether the download is part of an execution chain, not whether the utility is popular.
Command-line shape also matters. Look for flags and patterns that reduce friction, such as silent mode, redirecting output to a file, or pulling content directly from a raw URL into a file with a likely executable extension. Those patterns are often combined with living-off-the-land activity, so Living off the Land Guide is useful background for understanding why a benign binary can become part of an attack chain.
Which process and file signals matter most
The strongest indicators come from correlation. Watch for curl or wget opening outbound connections, then writing to paths such as %TEMP%, Downloads, AppData, Public, or other user-controlled locations, and then see whether a new binary or script is executed shortly after. The shorter the time gap between download and execution, the stronger the suspicion. If the file is renamed after download, or if it lands with a double-extension or unusual extension mix, that raises confidence further.
Also inspect the file itself. A downloaded payload that is unsigned, newly seen on the host, or inconsistent with the parent process’s normal purpose deserves closer review. If the download is followed by archive extraction, script interpreter launch, or a service or scheduled task modification, treat the whole sequence as one campaign rather than separate events.
Network context helps distinguish routine automation from abuse. Unusual domains, short-lived infrastructure, raw IP addresses, and obviously encoded or random-looking paths are all useful clues. Correlate the source with proxy, DNS, and endpoint telemetry so you can tell whether the host fetched a legitimate update, a staging payload, or a downloader used to bootstrap later activity.
How to investigate and confirm abuse
Start by building a timeline around the process creation event and the file-write event. Confirm the parent process, full command line, user context, and destination path, then look for the next executable action on that same host. If the downloaded file was opened by Explorer, cmd.exe, PowerShell, wscript, mshta, or another interpreter, that sequence usually matters more than the initial download alone.
Then test the source and the payload as one case. Check whether the domain is newly registered, whether the IP maps to cloud hosting or disposable infrastructure, and whether the file hash appears elsewhere in your environment. If the file was staged from a shared location or copied laterally after download, widen the hunt to adjacent hosts and accounts.
When the download is tied to a known malicious toolset or campaign style, review for the surrounding tradecraft as well. The MITRE ATT&CK Enterprise Matrix helps you map the behavior to download, execution, and persistence patterns so the hunt is not limited to one process event. For a download that arrives through an API, script, or automation chain, MITRE ATT&CK Enterprise Matrix helps you connect the fetch to the follow-on technique rather than stopping at the transfer itself.
Risk and Threat Considerations
File downloads via curl or wget become risky when they are used as a lightweight staging step for malware, credential theft, or later execution. The main danger is that these tools blend into normal administration, so defenders may miss the handoff from download to local execution until a payload is already on disk and running.
Failure mechanism: An attacker or intruder uses a trusted command-line downloader to retrieve a payload from infrastructure that looks ordinary at first glance, then writes it into a user-writable path and executes it with minimal visible interaction.
Impact: The host can receive a new binary or script with little friction, which increases the chance of execution, persistence, and subsequent discovery evasion. Once that pattern is established, the same technique can be reused for staging, post-exploitation tooling, or follow-on access.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK addresses the attack and risk surface, while CIS Controls v8 sets the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| MITRE ATT&CK | T1105 — Ingress Tool Transfer | Covers downloading payloads with command-line tools before execution. |
| T1059 — Command and Scripting Interpreter | Suspicious downloads often precede script or interpreter-based execution. | |
| T1106 — Native API | Windows tooling often uses native utilities or APIs to stage and launch payloads. | |
| Recommendation — Map curl and wget downloads to T1105 and hunt for the follow-on process execution. Correlate downloader activity with script interpreter launches and child process chains. Trace native utility use that writes a payload and then starts it locally. | ||
| CIS Controls v8 | CIS-8 — Audit Log Management | Endpoint and process logs are needed to correlate download, write, and execution events. |
| CIS-10 — Malware Defenses | Suspicious downloads are a common malware staging pattern that needs detection and response. | |
| Recommendation — Centralize process and file telemetry so downloader-to-execution chains are searchable. Tune malware defenses to flag user-writable payload drops from command-line downloaders. | ||
Practitioner Guidance
What to prioritise: Prioritise chains where download, file write, and execution occur in close succession on the same host. That sequence is usually more actionable than isolated curl or wget usage, especially when the destination is user-controlled storage rather than an approved software distribution path.
What to verify: Verify the source domain, destination path, command-line flags, and the first process that touches the downloaded file after creation. If those elements do not line up with normal admin or software delivery behavior, treat the event as a likely staging attempt and expand the hunt to related users and endpoints.
Practitioner takeaway: The decisive question is not whether curl or wget ran, but whether the download was immediately converted into execution on the local host. That transition is what turns a common utility into a high-value detection opportunity.
Related resources from NHI Mgmt Group
- What are the signs that file monitoring on Windows servers is failing to detect suspicious activity?
- How do you detect Encrypting File System RPC abuse such as PetitPotam on Windows?
- How do you detect suspicious OAuth app file download activity in Microsoft 365?
- How do you detect data exfiltration with wget or curl on Linux?
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Reviewed and updated by the NHIMG editorial team on October 20, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org