To answer this question, you need to understand the difference between an object infected by viruses and malicious software.
Typically, a virus adds (appends its code) to an infected file so it incorporates its own code and the virus's code. Together, they represent a virus-infected file. Most of these files can be cured (and are cured) by Dr.Web anti-virus. Here we are speaking about curing files of viruses rather than curing viruses.
Malicious software in itself operates as a separate computer program, so it cannot be cured but only removed. In some cases, we can speak about curing a system (but not malicious software). This includes removing the detected threat and restoring the compromised objects.
