I Did A Test: Some AV Software Just Report Shells

[aluckystar]

I tested a Hupigon (packed with 6 shells) on VirusTotal and I found that many antivirus software ( like Antivir,AVAST,Bitdefender,CAT,Kaspersky) can't recognize it. They can just report the shell. I tried a Nimda (packed with 12 shells), and I got the same result. Can somebody tell me why ?

~removed virustotal attachment per this policy - Ron~

[Sjoeii]

First of all maybe you can try the most recent Kaspersky engine?
I see 4.??

Maybe that's the issue why it's reported it like that

[solcroft]

I don't see why you say that many scanners can't detect your repacked sample. VT seems to show quite a lot of scanners picking it up.