Send a retrieved *.png file from REST API call to another system (base64)

Hello everyone,

I need to send *.png file from SMAX to another system as base64.

I've got attachment ID from SMAX by REST API request /rest/<tenantID>/ems/Request. Then I use the attachment ID in REST API request /rest/<tenantID>/ces/attachment/<attachment ID> and I recieve answer with the content in a format with special characters, it looks like this:

Moreover the content text can't be copied & pasted when there are more than one special character - rectangle in row, it always paste only "‰PNG".

Is there any way how to retrieve the file in base64?

Thank you for your help in advance.