Develop Reference

Why ManagementObjectSearcher call is insanely slow (30sec-2mins) [duplicate]

I am enumerating installed applications using WMI, and this block is taking a relatively long time to complete no matter how I structure it. It takes 13 seconds in my environment every time. Is there a better (faster) way to check if a program is installed? (I'm using iTunes as an example program to check for)
private static string Timestamp
{
get { return DateTime.Now.ToString("HH:mm:ss.ffff"); }
}
private static void LoadInstalledPrograms()
{
List<string> installedPrograms = new List<string>();
Console.WriteLine("0 - {0}", Timestamp);
ManagementObjectSearcher mos = new ManagementObjectSearcher("SELECT * FROM Win32_Product");
Console.WriteLine("1 - {0}", Timestamp);
ManagementObjectCollection managementObjectCollection = mos.Get();
Console.WriteLine("2 - {0}", Timestamp);
foreach (ManagementObject mo in managementObjectCollection)
{
installedPrograms.Add(mo["Name"].ToString());
}
Console.WriteLine("3 - {0}", Timestamp);
Console.WriteLine("Length - {0}", installedPrograms.Count);
}
SELECT * FROM Win32_Product
0 - 08:08:51.3762
1 - 08:08:51.3942
2 - 08:08:51.4012
3 - 08:09:04.8326
Length - 300
SELECT * FROM Win32_Product WHERE name = 'iTunes'
0 - 08:14:17.6529
1 - 08:14:17.6709
2 - 08:14:17.6779
3 - 08:14:31.0332
Length - 1
SELECT * FROM Win32_Product WHERE name LIKE 'iTunes'
0 - 08:16:38.2719
1 - 08:16:38.2899
2 - 08:16:38.2999
3 - 08:16:51.5113
Length - 1
SELECT name FROM Win32_Product WHERE name LIKE 'iTunes'
0 - 08:19:53.9144
1 - 08:19:53.9324
2 - 08:19:53.9394
3 - 08:20:07.2794
Length - 1

If you query "Win32_product" the msi-installer checks and validates every product.
The KB article http://support.microsoft.com/kb/974524 shows:
Win32_product Class is not query optimized. Queries such as “select * from Win32_Product where (name like 'Sniffer%')” require WMI to use the MSI provider to enumerate all of the installed products and then parse the full list sequentially to handle the “where” clause. This process also initiates a consistency check of packages installed, verifying and repairing the install. With an account with only user privileges, as the user account may not have access to quite a few locations, may cause delay in application launch and an event 11708 stating an installation failure.
Win32reg_AddRemovePrograms is a much lighter and effective way to do this, which avoids the calls to do a resiliency check, especially in a locked down environment. So when using Win32reg_AddRemovePrograms we will not be calling on msiprov.dll and will not be initiating a resiliency check.
So be careful with "Win32_product".
Update: nice article https://sdmsoftware.com/group-policy-blog/wmi/why-win32_product-is-bad-news/

WMI is taking it's time as you already noticed. Iterating through the registry might do the trick for you.
You might have a look at Get installed applications in a system here on stackoverflow, where both methods are mentioned.

As Bernhard points out, WMI use of Win32_Product initiates an integrity check of the package estate, and will hence be quite slow to use - and in special cases it can trigger an MSI self-repair (I have never seen this happen on my machines).
Instead of WMI, you can use the MSI automation interface directly to enumerate the applications installed via Windows Installer packages (MSI files) on the machine. This is very quick and doesn't touch WMI at all.
See this example: how to find out which products are installed - newer product are already installed MSI windows (full blown, but basic and easy to understand VBScript example - do check it out). There are many properties you can retrieve for each product, please consult the MSDN documentation for the MSI automation interface. The linked sample VBScript code and the MSDN documentation taken together should help you get going quickly I hope.
P.S: I know this is an old question, but this issue keeps coming up (specifically the slowness of WMI) - just for future reference.

As mentioned here Registry is not reliable and WMI is slow. Thus for me the best option was using Windows Installer API. Add msi.dll to your references and then adapt the following code to your needs:
public static string GetVersionOfInstalledApplication(string queryName)
{
string name;
string version;
Type type = Type.GetTypeFromProgID("WindowsInstaller.Installer");
Installer installer = Activator.CreateInstance(type) as Installer;
StringList products = installer.Products;
foreach (string productGuid in products)
{
string currName = installer.ProductInfo[productGuid, "ProductName"];
string currVersion = installer.ProductInfo[productGuid, "VersionString"];
if (currName == queryName)
{
name = currName;
version = currVersion;
return version;
}
}
return null;
}

You Should use SELECT Name FROM Win32_Product in WMI Query, it works for me
SELECT * make Load all Data Members, so using it are taking much time

Powershell 5.1 has "get-package" instead.
get-package *chrome*
Name Version Source ProviderName
---- ------- ------ ------------
Google Chrome 109.0.5414.75 msi

Lastlogon time on DC return different value in .Net and powershell

I'm writing a little application that can audit the lastlogon time of a user on every DC in our environment.
With a little help I was able to create a code that iterate all the DC's and query the lastlogon time of a user. As I read it before this value isn't synchronizing among the DC's and this is a by design by MS.
Here is the code I use to check a user on every DC:
foreach (string DCInstance in DC_Collection)
{
try
{
using (PrincipalContext context = new PrincipalContext(ContextType.Domain,DCInstance))
{
using (UserPrincipal userPrincipal = new UserPrincipal(context))
{
userPrincipal.Name = "TestUserName";
using (PrincipalSearcher searcher = new PrincipalSearcher(userPrincipal))
{
using (PrincipalSearchResult<Principal> results = searcher.FindAll())
{
foreach (UserPrincipal FoundUser in results)
{
Console.WriteLine(FoundUser.SamAccountName + "," + FoundUser.LastLogon + "," + DCInstance);
}
}
}
}
}
}
catch (PrincipalServerDownException PSDE)
{
MessageBox.Show(PSDE.Message + ": " + DCInstance);
}
}
I know that many of the brackets are unnecessary but it is just more readable to me this way.
This is the core of the program. However I recognized that the lastlogon time of the found user is the same on each DC instance, which is quite unlikely.
To make sure of this issue I made a little PS script that do the same thing, so I can compare the results. Here is the PS script:
foreach($dc in $dcs)
{
$hostname = $dc.HostName
$user = Get-ADUser $userName -Server $hostname | Get-ADObject -Properties lastLogon
}
Again this is only the core of the script that make the actual work.
The result however are completely differs. The PS script results the the times as I expected, quite different on almost every DC (not all differs from the others but most of them). The .Net program however returns the same time from all DC instances and in addition it returns a time that do not displays in the PS script!
Now I'm quite confused. I believe the PS script is the correct one, but then I really do not know what did I missed in the .Net version.
I did some debug on the program but the found user contains only the time that the program displays, and even the filetime value different from the PS version.
I even thought on date-time conversion issue, but then the structure of the result should be the same with different values, but they aren't.
Thx in advance for any sort of help.

I found the answer! :-)
I modified the C# code to return the filetime on the assumed Last logon data, and also did a detailed ps script to list every variable of the user so I can find the relevant property returned by the c#.
Here is a PS script:
Get-ADUser TestUser | Get-ADObject -Properties *
This line returns every property that is stored in the AD about the given user.
Among others there are two value I care about:
lastLogon and lastLogonTimestamp
After this I checked the filetime version of the lastlogon property returned by the c# and it turened out, that this value is actually the same with the lastLogonTimestamp and there is no (or I did not found) way to request the exact lastlogon data.
The proper solution is to redesign the code the operate with LDAP queries instead of API calls.
Little help for that can be found here

How can I find the SID for an app pool via Microsoft.Web.Administration?

I am working on a configuration tool that needs to set some permissions on a directory based on the identity that a specific web application runs under. The original code simply built the login name based on IIS APPPOOL\<ApppoolName> or based on the well know SID if it was a built in account.
Some similar code failed in a localized environment so I am now trying to get rid of the baked in string.
My solution was this:
public static SecurityIdentifier GetApplicationPoolSid(string name)
{
ApplicationPool pool = Manager.ApplicationPools[name];
if (pool != null)
{
var sddlForm = pool.GetAttributeValue("applicationPoolSid") as string;
if (!String.IsNullOrEmpty(sddlForm))
return new SecurityIdentifier(sddlForm);
}
return null;
}
The problem is that I found "applicationPoolSid" by poking around in the debugger and I cannot find any documentation that says that I am not taking advantage of an undocumented implementation feature that will go away in the future. (This means it won't pass code review.)
I would love to know the approved way of doing what I am looking at here. I would also be happy to know that IIS APPPOOL\<ApppoolName> is guaranteed to never be localized so then we could go back to the old way.

I can find no reference to IIS APPPOOL being localized, which would make sense since neither IIS nor APPPOOL are words in any language, so there's nothing to translate to. Although they are acronyms in English and possibly other languages, I think they are still called IIS and AppPool even in other languages.
You can, by the way, get the SID officially like this:
NTAccount f = new NTAccount(#"IIS AppPool\DefaultAppPool");
SecurityIdentifier s = (SecurityIdentifier)f.Translate(typeof(SecurityIdentifier));
String sidString = s.ToString();
You don't even really need the SID if you're going to pass it to FileSystemAccessRule(), since it has an overload that takes an IdentityReference, which NTAccount is. Just pass it the NTAccount.

This will get you the SID, but does not use the function you asked about and is written in powershell not C#. I am posting this to hopefully assist in getting on the right track regarding the generation using SHA1 rather than actually querying from Windows. Also some systems do not have some SID and user account modules installed so this can be used in those situations.
Function to generate SID based off apppool username (explanation in link at the bottom)
function Get-SID ([String]$winver, [String]$username) {
$sidPrefix = switch ($winver) {
'6.0' { 'S-1-5-80' }
default { 'S-1-5-82' }
}
$userToString = switch ( $sidPrefix ) {
'S-1-5-82' { $username.ToLower() }
default { $username.ToUpper() }
}
$userBytes = [Text.Encoding]::Unicode.GetBytes($userToString)
$sha = New-Object System.Security.Cryptography.SHA1CryptoServiceProvider
$hash = $sha.ComputeHash($userBytes)
$sid = $sidPrefix
for ( $i=0; $i -lt 5; $i++ ) {
$sid += '-' + [BitConverter]::ToUInt32($hash, $i*4)
}
return $sid
}
Example usage
Get-SID -winver "6.0" -username "DefaultAppPool"
User 6.0 for Vista or equivalent release, use 6.1/6.2 etc for after that.
Partial credit to Tomas Restrepo from winterdom.com for the powershell, although that script does not actually work because some functions are not included in the code.

.NET virus scanning API

I'm building a web application in which I need to scan the user-uploaded files for viruses.
Does anyone with experience in building something like this can provide information on how to get this up and running? I'm guessing antivirus software packages have APIs to access their functionality programatically, but it seems it's not easy to get a hand on the details.
FYI, the application is written in C#.

Important note before use:
Be aware of TOS agreement. You give them full access to everything: "When you upload or otherwise submit content, you give VirusTotal (and those we work with) a worldwide, royalty free, irrevocable and transferable licence to use, edit, host, store, reproduce, modify, create derivative works, communicate, publish, publicly perform, publicly display and distribute such content."
Instead of using a local Antivirus program (and thus binding your program to that particular Antivirus product and requesting your customers to install that Antivirus product) you could use the services of VirusTotal.com
This site provides a free service in which your file is given as input to numerous antivirus products and you receive back a detailed report with the evidences resulting from the scanning process. In this way your solution is no more binded to a particular Antivirus product (albeit you are binded to Internet availability)
The site provides also an Application Programming Interface that allows a programmatically approach to its scanning engine.
Here a VirusTotal.NET a library for this API
Here the comprensive documentation about their API
Here the documentation with examples in Python of their interface
And because no answer is complete without code, this is taken directly from the sample client shipped with the VirusTotal.NET library
static void Main(string[] args)
{
VirusTotal virusTotal = new VirusTotal(ConfigurationManager.AppSettings["ApiKey"]);
//Use HTTPS instead of HTTP
virusTotal.UseTLS = true;
//Create the EICAR test virus. See http://www.eicar.org/86-0-Intended-use.html
FileInfo fileInfo = new FileInfo("EICAR.txt");
File.WriteAllText(fileInfo.FullName, #"X5O!P%#AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*");
//Check if the file has been scanned before.
FileReport fileReport = virusTotal.GetFileReport(fileInfo);
bool hasFileBeenScannedBefore = fileReport.ResponseCode == ReportResponseCode.Present;
Console.WriteLine("File has been scanned before: " + (hasFileBeenScannedBefore ? "Yes" : "No"));
//If the file has been scanned before, the results are embedded inside the report.
if (hasFileBeenScannedBefore)
{
PrintScan(fileReport);
}
else
{
ScanResult fileResult = virusTotal.ScanFile(fileInfo);
PrintScan(fileResult);
}
... continue with testing a web site ....
}
DISCLAIMER
I am in no way involved with them. I am writing this answer just because it seems to be a good update for these 4 years old answers.

You can use IAttachmentExecute API.
Windows OS provide the common API to calling the anti virus software which is installed (Of course, the anti virus software required support the API).
But, the API to calling the anti virus software provide only COM Interface style, not supported IDispatch.
So, calling this API is too difficult from any .NET language and script language.
Download this library from here Anti Virus Scanner for .NET or add reference your VS project from "NuGet" AntiVirusScanner
For example bellow code scan a file :
var scanner = new AntiVirus.Scanner();
var result = scanner.ScanAndClean(#"c:\some\file\path.txt");
Console.WriteLine(result); // console output is "VirusNotFound".

I would probably just make a system call to run an independent process to do the scan. There are a number of command-line AV engines out there from various vendors.

Take a look at the Microsoft Antivirus API. It makes use of COM, which should be easy enough to interface with from .NET. It refers specifically to Internet Explorer and Microsoft Office, but I don't see why you wouldn't be able to use to to on-demand scan any file.
All modern scanners that run on Windows should understand this API.

Various Virus scanners do have API's. One I have integrated with is Sophos. I am pretty sure Norton has an API also while McAfee doesn't (it used to). What virus software do you want to use? You may want to check out Metascan as it will allow integration with many different scanners, but there is an annual license cost. :-P

I also had this requirement. I used clamAv anti virus which provides on-demand scanning by sending the file to their tcp listening port. You can use nClam nuget package to send files to clamav.
var clam = new ClamClient("localhost", 3310);
var scanResult = clam.ScanFileOnServerAsync("C:\\test.txt"); //any file you would like!
switch (scanResult.Result.Result)
{
case ClamScanResults.Clean:
Console.WriteLine("The file is clean!");
break;
case ClamScanResults.VirusDetected:
Console.WriteLine("Virus Found!");
Console.WriteLine("Virus name: {0}", scanResult.Result.InfectedFiles[0].FileName);
break;
case ClamScanResults.Error:
Console.WriteLine("Woah an error occured! Error: {0}", scanResult.Result.RawResult);
break;
}
A simple and detailed example is shown here. Note:- The synchronous scan method is not available in the latest nuget. You have to code like I done above
For testing a virus you can use the below string in a txt file
X5O!P%#AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*

Shameless plug but you might want to check out https://scanii.com, it's basically malware/virus detection as a (REST) service. Oh also, make sure you read and understand virustotal's API terms (https://www.virustotal.com/en/documentation/public-api/) - they are very clear about not allowing commercial usage.

I would recommend using this approach:
using System;
using System.Diagnostics;
using Cloudmersive.APIClient.NET.VirusScan.Api;
using Cloudmersive.APIClient.NET.VirusScan.Client;
using Cloudmersive.APIClient.NET.VirusScan.Model;
namespace Example
{
public class ScanFileAdvancedExample
{
public void main()
{
// Configure API key authorization: Apikey
Configuration.Default.AddApiKey("Apikey", "YOUR_API_KEY");
var apiInstance = new ScanApi();
var inputFile = new System.IO.FileStream("C:\\temp\\inputfile", System.IO.FileMode.Open); // System.IO.Stream | Input file to perform the operation on.
var allowExecutables = true; // bool? | Set to false to block executable files (program code) from being allowed in the input file. Default is false (recommended). (optional)
var allowInvalidFiles = true; // bool? | Set to false to block invalid files, such as a PDF file that is not really a valid PDF file, or a Word Document that is not a valid Word Document. Default is false (recommended). (optional)
var allowScripts = true; // bool? | Set to false to block script files, such as a PHP files, Pythong scripts, and other malicious content or security threats that can be embedded in the file. Set to true to allow these file types. Default is false (recommended). (optional)
var allowPasswordProtectedFiles = true; // bool? | Set to false to block password protected and encrypted files, such as encrypted zip and rar files, and other files that seek to circumvent scanning through passwords. Set to true to allow these file types. Default is false (recommended). (optional)
var restrictFileTypes = restrictFileTypes_example; // string | Specify a restricted set of file formats to allow as clean as a comma-separated list of file formats, such as .pdf,.docx,.png would allow only PDF, PNG and Word document files. All files must pass content verification against this list of file formats, if they do not, then the result will be returned as CleanResult=false. Set restrictFileTypes parameter to null or empty string to disable; default is disabled. (optional)
try
{
// Advanced Scan a file for viruses
VirusScanAdvancedResult result = apiInstance.ScanFileAdvanced(inputFile, allowExecutables, allowInvalidFiles, allowScripts, allowPasswordProtectedFiles, restrictFileTypes);
Debug.WriteLine(result);
}
catch (Exception e)
{
Debug.Print("Exception when calling ScanApi.ScanFileAdvanced: " + e.Message );
}
}
}
}
Note that this way you can even control whether you filter out non-virus threat payloads such as executables, scripts, encrypted/password-protected files, etc.
This approach has a free tier and can also validate the contents of the files that you upload.

We tried two options:
clamav-daemon installed on a tiny linux container + "nClam" .NET library to interact with it. Works fine, but Clam AV misses a lot (a lot!) of viruses, especially dangerous macros hidden in MS Office files. Also ClamAV virus database has to be kept in memory at all times, which uses around 3.5GB of memory, which requires a rather expensive cloud virtual machine.
Ended up using Windows Defender via MpCmdRun.exe CLI api. See answer here

You can try to use DevDragon.io.
It is a web service with an API and .NET client DevDragon.Antivirus.Client you can get from NuGet. Scans are sub 200ms for 1MB file.
More documentation here:
https://github.com/Dev-Dragon/Antivirus-Client
Disclosure: I work for them.

From my experience you can use COM for interfacing with some anti-virus software. But what I would suggest is a bit easier, just parse scan results after scanning. All you need to do is to start the scanner process and point it to file/folder you want to scan, store scan results into file or redirect stdout to your application and parse results.

//Scan
string start = Console.ReadLine();
System.Diagnostics.Process scanprocess = new System.Diagnostics.Process();
sp.StartInfo.WorkingDirectory = #"<location of your antivirus>";
sp.StartInfo.UseShellExecute = false;
sp.StartInfo.FileName = "cmd.exe";
sp.StartInfo.Arguments = #"/c antivirusscanx.exe /scan="+filePath;
sp.StartInfo.CreateNoWindow = true;
sp.StartInfo.RedirectStandardInput = true;
sp.StartInfo.RedirectStandardError = true; sp.Start();
string output = sp.StandardOutput.ReadToEnd();
//Scan results
System.Diagnostics.Process pr = new System.Diagnostics.Process();
pr.StartInfo.FileName = "cmd.exe";
pr.StartInfo.Arguments = #"/c echo %ERRORLEVEL%";
pr.StartInfo.RedirectStandardInput = true;
pr.StartInfo.RedirectStandardError = true; pr.Start();
output = processresult.StandardOutput.ReadToEnd();
pr.Close();

What is the Fastest way to read event log on remote machine?

I am working on an application which reads eventlogs(Application) from remote machines. I am making use of EventLog class in .net and then iterating on the Log entries but this is very slow. In some cases, some machines have 40000+ log entries and it takes hours to iterate through the entries.
what is the best way to accomplish this task? Are there any other classes in .net which are faster or in any other technology?

Man, I feel your pain. We had the exact same issue in our app.
Your solution has a branch depending on what server version you're running on and what server version your "target" machine is running on.
If you're both on Vista or Windows Server 2008, you're in luck. You should look at System.Diagnostics.Eventing.Reader.EventLogQuery and System.Diagnostics.Eventing.Reader.EventLogReader. These are new in .net 3.5.
Basically, you can build a query in XML and ship it over to run on the remote computer. Maybe you're just searching for events of a specific type, or maybe just new events from a specific point in time. The search runs on the remote machine, and then you just get back the matching events. The new classes are much faster than the old .net 2.0 way, but again, they are only supported on Vista or Windows Server 2008.
For our app when the target is NOT on Vista/Win2008, we downloaded the raw .evt file from the remote system, and then parsed the file using its binary format. There are several sources of data about the event log format for .evt files (pre-Vista), including link text and an article I recall on codeproject.com that had some c# code.
Vista and Windows Server 2008 machines use a new .evtx format that is a new format, so you can't use the same binary parsing approach across all versions. But the new EventLogQuery and EventLogReader classes are so fast that you won't have to. It's now perfectly speedy to just use the built-in classes.

Event Log Reader is horribly slow... too slow. WTF Microsoft?
Use LogParser 2.2 - Search for C# and LogParser on the Internet (or you can use the log parser commands from the command line). I don't want to duplicate the work already contributed by others.
I pull the log from the remote system by having the log exported as an EVTX file. I then copy the file from the remote system. This process is really quick - even with a network that spans the planet (I had issues with having the log exported to a network resource). Once you have it local, you can do your searches and processing.
There are multiple reasons for having the EVTX - I won't get into the reasons why we do this.
The following is a working example of the code to save a copy of the log as an EVTX:
(Notes: "device" is the network host name or IP. "LogName" is the name of the log desired: "System", "Security", or "Application". outputPathOnRemoteSystem is the path on the remote computer, such as "c:\temp\%hostname%.%LogName%.%YYYYMMDD_HH.MM%.evtx".)
static public bool DumpLog(string device, string LogName, string outputPathOnRemoteSystem, out string errMessage)
{
bool wasExported = false;
string errorMessage = "";
try
{
System.Diagnostics.Eventing.Reader.EventLogSession els = new System.Diagnostics.Eventing.Reader.EventLogSession(device);
els.ExportLogAndMessages(LogName, PathType.LogName, "*", outputPathOnRemoteSystem);
wasExported = true;
}
catch (UnauthorizedAccessException e)
{
errorMessage = "Unauthorized - Access Denied: " + e.Message;
}
catch (EventLogNotFoundException e)
{
errorMessage = "Event Log Not Found: " + e.Message;
}
catch (EventLogException e)
{
errorMessage = "Export Failed: " + e.Message + ", Log: " + LogName + ", Device: " + device;
}
errMessage = errorMessage;
return wasExported;
}

A good Explanation/Example can be found on MSDN.
EventLogSession session = new EventLogSession(Environment.MachineName);
// [System/Level=2] filters out the errors
// Where "Log" is the log you want to get data from.
EventLogQuery query = new EventLogQuery("Log", PathType.LogName, "*[System/Level=2]");
EventLogReader reader = new EventLogReader(query);
for (EventRecord eventInstance = reader.ReadEvent();
null != eventInstance;
eventInstance = reader.ReadEvent())
{
// Output or save your event data here.
}
When waiting 5-20 minutes with the old code this one does it in less than 10 seconds.

Maybe WMI can help you:
WMI with C#

Have you tried using the remoting features in powershell 2.0? They allow you to execute cmdlets (like ones to read event logs) on remote machines and return the results (as objects, of course) to the calling session.

You could place a Program at those machines that save the log to file and sends it to your webapplication i think that would be alot faster as you can do the looping local but im not sure how to do it so i cant ive you any code :(

I recently did such thing via WCF callback interface however my clients interacted with the server through WCF and adding a WCF Callback was easy in my project, full code with examples is available here

Just had the same issue and want to share my solution. It makes a search through application, system and security eventlogs from 260 seconds (using EventLog) about a 100 times faster (using EventLogQuery).
And this in a way where it is possible to check if the event message contains a pattern or any other check without the requirement of FormatDescription().
My trick is to use the same mechanism as PowerShells Get-WinEvent does and then pass it through the result check.
Here is my code to find all events within last 4 days where the event message contains a filter pattern.
string[] eventLogSources = {"Application", "System", "Security"};
var messagePattern = "*Your Message Search Pattern*";
var timeStamp = DateTime.Now.AddDays(-4);
var matchingEvents = new List<EventRecord>();
foreach (var eventLogSource in eventLogSources)
{
var i = 0;
var query = string.Format("*[System[TimeCreated[#SystemTime >= '{0}']]]",
timeStamp.ToUniversalTime().ToString("o"));
var elq = new EventLogQuery(eventLogSource, PathType.LogName, query);
var elr = new EventLogReader(elq);
EventRecord entryEventRecord;
while ((entryEventRecord = elr.ReadEvent()) != null)
{
if ((entryEventRecord.Properties)
.FirstOrDefault(x => (x.Value.ToString()).Contains(messagePattern)) != null)
{
matchingEvents.Add(entryEventRecord);
i++;
}
}
}

Maybe that the remote computers could do a little bit of computing. So this way your server would only deal with relevant information. It would be a kind of cluster using the remote computer to do some light filtering and the server would the the analysis part.