Logman.exe: Windows Performance Log Manager

logman.exe is a powerful command-line utility built into Windows operating systems. It's the primary tool for creating and managing Event Trace Session (ETW) logs, Data Collector Sets (DCS), and performance counter data. It's not a virus, nor can it be "turned into" a virus. It's a legitimate and essential part of Windows system administration.

Origin and Purpose

logman.exe is a native Windows component, developed by Microsoft. It's included in all modern Windows versions, from Windows XP and Server 2003 onwards, including Windows 10, 11, and server equivalents. Its primary purpose is to provide a command-line interface for interacting with the Windows Performance Monitor's (Perfmon) underlying data collection mechanisms. While Perfmon offers a graphical user interface, logman.exe provides greater flexibility, automation capabilities, and the ability to manage logging remotely.

Is it a Virus? Is it Vulnerable?

No, logman.exe is not a virus. It's a legitimate Microsoft-signed executable. Its presence in the C:\Windows\System32 directory (and C:\Windows\SysWOW64 on 64-bit systems) is normal and expected.

Can it become a virus? No. logman.exe itself cannot be modified to become malicious without compromising the digital signature, which Windows actively checks. However, it could be misused by malicious actors. For instance, an attacker could use logman.exe to create a trace that captures sensitive data, if they already have administrative privileges. The threat isn't logman.exe itself, but rather the potential for its misuse by someone with unauthorized access. Standard security practices (least privilege, strong passwords, up-to-date antivirus) mitigate this risk. logman.exe is as vulnerable as any other Windows component to system-level exploits, but it's not inherently more vulnerable than other command-line tools.

Usage and Examples

logman.exe is used from the command line (Command Prompt or PowerShell, typically run as an administrator). Here's a breakdown of its common uses and examples:

1. Creating Data Collector Sets (DCS):

A Data Collector Set is a grouping of performance counters, event trace providers, and/or configuration information that you want to collect.

Create a basic performance counter DCS:

powershell logman create counter MyPerformanceCounter -c "\Processor(_Total)\% Processor Time" "\Memory\Available MBytes" -si 00:00:05 -o "C:\PerfLogs\MyPerfCounter.blg"
- create counter: Specifies that we're creating a counter-based DCS.
- MyPerformanceCounter: The name of the DCS (user-defined).
- -c: Specifies the performance counters to collect. You can specify multiple counters. Use typeperf -qx to list all available counters.
- \Processor(_Total)\% Processor Time: Collects the total CPU usage.
- \Memory\Available MBytes: Collects available memory.
- -si: Sampling interval (hh:mm:ss). Here, it's 5 seconds.
- -o: Output file path and name. .blg is the standard binary log format.
Create an event trace DCS:

powershell logman create trace MyEventTrace -p "Microsoft-Windows-Kernel-Process" (Process,Thread) -o "C:\PerfLogs\MyEventTrace.etl"
- create trace: Specifies we are creating an event trace DCS.
- MyEventTrace: The name of the DCS.
- -p: Specifies the Event Trace Provider. Use logman query providers to list available providers.
- "Microsoft-Windows-Kernel-Process": The provider for kernel process events.
- (Process,Thread): Keywords to filter events from this provider. These are provider-specific.
- -o: Output file path and name. .etl is the standard Event Trace Log format.
- -ets : Start the trace session immediately.
Create a DCS from a template: logman create counter MyPerfCounter -v mmddhhmm -cf perf_counters.xml
- -cf: Specify a template file (.xml) that defines the DCS. This allows for complex configurations to be easily reused.

2. Starting and Stopping Data Collection:

Start a DCS:

powershell logman start MyPerformanceCounter
Stop a DCS:

powershell logman stop MyPerformanceCounter

3. Querying Existing Data Collector Sets:

List all DCS:

powershell logman query
Get detailed information about a specific DCS:

powershell logman query MyPerformanceCounter * List available providers:

powershell logman query providers
List providers with details:

powershell logman query providers -ets

4. Managing Existing Data Collector Sets:

Update a DCS (e.g., change the sampling interval):

powershell logman update MyPerformanceCounter -si 00:00:10
Delete a DCS:

powershell logman delete MyPerformanceCounter

5. Advanced Options:

-f <format>: Specifies the output file format (e.g., bin, csv, tsv, sql). The default for counters is usually .blg.
-max <size>: Sets the maximum size of the log file (in MB).
-m <[start | stop] [manual | schedule]>: Defines the start and stop mode (manual or scheduled).
-s <computer>: Specifies a remote computer to manage. Requires appropriate permissions.
-config <filename>: Uses a configuration file to define the DCS settings.

6. Using -ets The -ets option is short for "Event Trace Session". It tells logman to interact directly with the running trace session. This is important for commands like logman query providers -ets, which needs to query active providers to get detailed information like keywords, levels and enabled flags. Without -ets in such a case, you would only see a basic list of registered providers.

Troubleshooting

"Access Denied" Errors: Ensure you are running the command prompt or PowerShell as an administrator.
Counter Not Found: Verify the counter path using typeperf -qx. Counter names can vary slightly between systems.
Provider Not Found: Use logman query providers to check if the provider is registered. Some providers may only be available on specific Windows versions or with certain software installed.
Output File Not Created: Check that the output directory exists and that you have write permissions to it.
Circular Logging Issues: If using circular logging (-max with a file size limit), be aware that old data will be overwritten.

Conclusion