I really don't know why someone would want to steal your logo. However, if you are terribly concerned about it (I seriously would not be) then include it after the hire when you will be under NDA (for what that's worth).
To answer your question, "could they steal it"? Yes, they surly could. Of course anyone seeing your logo on the Internet could steal it as well. Logos are generally meant to be seen by the public. The public extends far beyond Upwork.
re: "Is it a bad idea to attach a picture of my logo when posting a job? I want to show it for a sample"
It is not a bad idea. It is a very good idea.
The biggest "risk" would be that a freelancer - acting inappropriately - might do the work for free and send it to you.
I'm not sure why you are worried about someone "stealing" your company's log. Companies such as Coca-Cola pay a lot of money just to have their logos displayed as many places as possible.
Stephen C wrote:
I want freelancers improve a logo i made, but will sharing it publicly be a bad idea? could they steal it?
Stephen, Please do share the logo you want improved. The danger of your logo being stolen is only as high as any other logo's like Adidas or Facebook or Twitch. I can talk only of my own practices and I never apply to a job to improve a logo if I don't see what I will improve. If the title of a job attracts my interest, before reading that I always check to see if they have attachments or not and if they don't have any attachments or sample links I close the page without wasting any further time.
Look at that from our (freelancers') view please. How much time does it take to read 30 jobs or how much time it takes to apply to one? If you want to get applications from good freelancers you should give as much information as possible. I don't apply to jobs I don't believe I can deliver with 100% client satisfaction. If I don't know 100% what a job is I can't be sure I can give 100% so I just close the window.
You could make a copy of your logo that does not allow copying, printing, or editing. I don't know what format this might be for an image, but I've done it with text documents—maybe you could just put the image in a password-protected DOCX or PDF?
re: "You could make a copy of your logo that does not allow copying, printing, or editing. I don't know what format this might be for an image, but I've done it with text documents—maybe you could just put the image in a password-protected DOCX or PDF?"
The name of this format for images is "imaginary."
As a graphic design freelancer, the more information you can give the designer in your job listing, the better. Some of us are super typographically oriented (me); others lean towards more illustrative designs. For us to know how well we can help you, it is very helpful for us to see your current design as well as other designs you like that are similar in style.
Any designer with integrity will not steal your work, and most logos are pretty specific to the company anyway; e.g. even if you steal the Nike swoosh or the NBC peacock, what can you do with it?