Writing to the registry - from a service !

Posted on 2004-09-12
Medium Priority
Last Modified: 2010-04-01
   I'm building a windows service. I need to write some entries to the registry. I used the SDK functions RegOpenKey, RegSetValue etc...but the registry is not getting updated :-(   Thing is that the same piece of code works fine when I run it as an EXE or as a DLL! There is no exceptions thrown also !  Ne idea about this one?

Question by:manoj_johar
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Expert Comment

ID: 12041618
A service needs a valid account when accessing resources like network or registry.

You either should stop the service using GUI applet of Service Control Manager (SCM) and restart it by giving a valid user account or give account information other than LocalSystem account when installing the service.

Regards, Alex

Author Comment

ID: 12041640
Local System account has the highest privileges right? There shouldnt be a problem when I use that I guess?
Funny thing is that I'm able to read from the registry but not able to write to it !
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Accepted Solution

itsmeandnobodyelse earned 1500 total points
ID: 12041658
It's has less to do with priviliges but that the system has to know *which* user rights the service is supposed to get.

I would recommend the GUI approach as you don't need to hold a valid user password in your program and have to make the logon only once.

Note, if you have a domain user, you have to define like  domain\username.

Regards, Alex

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Expert Comment

ID: 12041694
>> Funny thing is that I'm able to read from the registry but not able to write to it !

The registry has two parts - a system part and a user part. Services get started to a time where no user is logged in. Then, only the system part of the registry would have been available.

The concept to give write access only if a valid user could be provided  is necessary for the security concept of the registry. You'll have similar problems with file access and network access as there is no way to define access rights of LocalSystem account.

Regards, Alex

LVL 86

Expert Comment

ID: 12043559
Check the return values from the API functions. Chances are that you are writing to a key that requires administrative provileges or is secured in a different way. Also check that using RegMon (http://www.sysinternals.com/ntw2k/source/regmon.shtml). And, post some code :o)

Expert Comment

ID: 12052906
I think that it is because "Local Service" account under which services particulary run has access to other registry account than logged on user. Check the article:

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