NOTE: I am New contributor, if the question needs some improvement please tell in comment before down voting!
Usually I see messages on whatsapp and sometime on some other forums stating that forward this message to Ten or Twenty people and don't ignore. Apparently, there is nothing visible that could benefit that message writer. But still people write and innocent people do forward it. Yes, sometimes they include links saying click and get recharge which is obviously risky but I am more interested in the one that don't contain any link or are even voice notes.
Example:
✅ FINAL NOTICE "Dont ignore please read it carefully" Hello, I. Am JUAN CARLOS director of whatsapp, this message is to inform all of our users that we have sold whatsapp to Mark Zuckerberg for 19 billion $. WhatsApp is now controlled by mark zuckerberg. If you have at least 20 contacts send this sms and logo of your whatsapp will change to a new icon with facebook's "f" within 24 hours.Forward this message to more than 10 people to activate your new whatsapp with facebook services or else your account will be deleted from new servers. This is the final notice! Hello everyone, it seems that all the warnings were real, the use of WhatsApp cost money from summer 2017. If you send this string to 20 different on your list, your icon will be blue and will be free for you. If you do not believe me see tomorrow at 6 pm ending WhatsApp and have to pay to open it, this is by law This message is to inform all of our users, our servers have recently been very congested, so we are asking you to help us solve this problem. We require our active users to forward this message to each of the people in your contact list to confirm our active users using WhatsApp, if you do not send this message to all your contacts WhatsApp will then start to charge you. Your account will remain inactive with the consequence of losing all your contacts. Message from Jim Balsamic (CEO of Whatsapp ) we have had an over usage of user names on whatsapp Messenger. We are requesting all users to forward this message to their entire contact list. If you do not forward this message, we will take it as your account is invalid and it will be deleted within the next 48 hours. Please DO NOT ignore this message or whatsapp will no longer recognise your activation. If you wish to re-activate your account after it has been deleted, a charge of 25.00 will be added to your monthly bill. We are also aware of the issue involving the pictures updates not showing. We are working diligently at fixing this problem and it will be up and running as soon as possible. Thank you for your cooperation from the Whatsapp team” WhatsApp is going to cost us money soon. The only way that it will stay free is if you are a frequent user i.e. you have at least 10 people you are chatting with. To become a frequent user send this message to 10 people who receive it (2 ticks) and your WhatsApp logo should turn blue.
Forward this message to all WhatsApp contact.
Some other samples are here.
Edit:
The question is about "real" software virus. Is there some way to attach malicious content alongside a forward message to steal information or harm other devices. Because as in example, sometime it does not contain even a link to click but only alphabets.