Claim
There are reports from various people, that YAcoin has built in wallet stealer.

What you can do
It's a common feature for malware to activate its main task on random date, and add a mark to the computer so it doesn't do the same thing twice (like uploading the stolen wallet.dat twice after your wallet is already uploaded, it's a waste of resource).
Since you can't be too safe, if you have run YAcoin's client or modified minerd.exe and don't encrypt your wallet, make sure you install Bitcoin in another clean computer and send your bitcoin there.
Make sure you password protected your wallet on that new computer.

Does YACoin really have malware module in it ?
Who knows, it's possible that it's a joke, someone wants to drop YAC's price on orderbook.
Or, it's the real deal. The attackers want people to believe that all of the various malware report that we receive now is a joke, and further report will be ignored once the real attack is really launched.
Hence, the investigation.

Investigation
I'll list what I found here :

List of YACoin related binary

yacoin-qt-2013-05-08.zip (yacoin's main client, uploaded during YACoin launch)
https://mega.co.nz/#!UowEmZYS!AAK7DVwYoTqy96oTRzUaLCS0UMsAfosJiRQmBn1jzcA
Detection ratio : 0 / 46 https://www.virustotal.com/en/file/7381b3ea8e872d860cf8279b98cb74a01cd21ecebaa1af7e537a040b6c5ad1e7/analysis/1368286925/

yacoin-qt-2013-05-09.zip (yacoin's main client, updated binary)
https://mega.co.nz/#!5wgDnKyZ!QLfWTXNRMRTwmb60rfpuFgzH48BCl4fpwb8paeAaqRs
Detection ratio : 0 / 46 https://www.virustotal.com/en/file/8c1b9dcc90e163a357b3861c10d8cec67c351a928e0b5e1e0dcf74d65d4a4b76/analysis/

cpuminer-scrypt-jane-win32.zip (modified minerd to mine yacoin on multiple computer)
hxxp://mega.co.nz/#!IJRziTBD!ZCAKGC7fqYkyXsEDi9GB1RYiqIUqj2S9bEm6UI2y1no
Detection ratio : 6 / 46 https://www.virustotal.com/en/file/2b7e630cfb2d173eb14e4dd88a7879527f5c52cbc77ace0c0742942aad46faec/analysis/1368286565/

"antivirus friendly" version of minerd (don't download this, very suspicious)
hxxp://mega.co.nz/#!shoxkb5b!DjiCAQBQ627TaW0oet1C7mvqM7Q2-2u-g4kDRHbniU4
From : https://bitcointalk.org/index.php?topic=201050.0
Detection ratio : 16 / 46 https://www.virustotal.com/en/file/0ffa2116bf1027019ad94e9bf8e2340be427d6efbc9563e185096cf8550b4c3a/analysis/1368287421/

minerd_scrypt_jane.ZIP (another modified minerd to mine yacoin on multiple computer)
https://mega.co.nz/#!pUMBkbbY!cMJYcFqPCMr1idZBr30VsFw0tLY7y63J0N4RVNYMUBc
Detection ratio : 0 / 46 https://www.virustotal.com/en/file/01a79a608d33d1db4eb9382db029e89e581f6e0017ddb566e7826b45370596fd/analysis/

All investigation should be done in clean Virtual Machine, otherwise, it's useless since it's possible that your computer is already marked and the malware won't run wallet stealing routine twice.

"Victim" List - Alternate cryptocurrency section

FreeTibet / Jr. Member / Posts: 11 / DO NOT DOWNLOAD YACOIN - SENDS WALLET.DAT TO http://bitcoin-ticker.netne.net/u.p

Quote from: FreeTibet on May 11, 2013, 12:33:46 PM

Don't download yacoin Windows binary.. it sends your bitcoin wallet.dat to this page: http://bitcoin-ticker.netne.net/u.php

I observed it with Fiddler. Stay safe, compile the code yourself!

Lewies Man / Jr Member / Posts: 45 / 2.374 bitcoins stolen after downloading yacoin

Quote from: LewiesMan on May 11, 2013, 12:32:08 PM

2.374 bitcoins stolen .. anyone can help?? the last thing I did on this computer was install yacoin..

i didn't have passphrase set but i do have now. yacoin has virus? stole my coins

Brewins / Jr. Member / Posts: 69 / Yacoin developer stole more than 256 BTC!

Quote from: Brewins on May 11, 2013, 12:56:32 PM

My coins were sent to this address:

https://blockchain.info/address/1Ay1fS9b6TZbXEEeihGCLo1oG7zpSiChSf

If you see this transaction more than 256 btc has being stolen https://blockchain.info/tx/11b3704b041ebfc8772f43116b69dc70345f1a6c4a873774e6d087a5f6e6691d

D35TR0Y3R / Full Member / Posts: 108 / WARNING: YACOIN HAS A VIRUS BITCOIN STEALER

Quote from: D35TR0Y3R on May 11, 2013, 01:37:07 PM

I HAVE LOST MY BITCOINS IT HAS BEING SENT TO https://blockchain.info/address/1RPrtamTACe1TcqkX2FmWVtRzmQJ6CfRx

UNINSTALL AND DON'T RUN YACOIN

nocompare / Jr. Member / Posts: 14 / yacoin developers are a bunch of crooks, steals 900 BTC

Quote from: nocompare on May 11, 2013, 01:49:50 PM

https://blockchain.info/address/1RPrtamTACe1TcqkX2FmWVtRzmQJ6CfRx

I am quitting bitcoin.. Lost bitcoin in bitcoin 24.. lost bitcoin in blockbet.. NOW SOMEONE HACK MY WALLET

"Victim List" - Newbie section

moneytronics / Posts: 1 / YACOIN STEALS YOUR WALLET DO NOT USE

Quote from: moneytronics on May 11, 2013, 01:08:52 PM

BITCOINS GONE!

TX ID 11b3704b041ebfc8772f43116b69dc70345f1a6c4a873774e6d087a5f6e6691d

DO NOT USE

jebwizoscar / Posts: 5 / yacoin trojan

Quote from: jebwizoscar on May 11, 2013, 01:12:16 PM

yacoin is sending my coins

danieljoseph / Posts: 1 / yacoin stole my 14.25 btc

Quote from: danieljoseph on May 11, 2013, 01:42:04 PM

What do I do now? I downloaded Yacoin which had a wallet stealer in it. Can I get my coins back? Should I file a police report?

SquishySquish / Posts: 6 / bitcoin sent from my wallet?

Quote from: SquishySquish on May 11, 2013, 01:10:02 PM

my bitcoins have being sent from my wallet

is it the alt coins I downloaded?

netne.net Whois

Quote

Registered through: GoDaddy.com, LLC (http://www.godaddy.com)
Domain Name: NETNE.NET
Created on: 19-Mar-09
Expires on: 19-Mar-14
Last Updated on: 20-Mar-13

Registrant:
Hostinger International Ltd.

61 Lordou Vyronos
Larnaca, 6023
Cyprus

Administrative Contact:
Kyriako, Kyriakos hostmaster@hostinger.com
Hostinger International Ltd.
61 Lordou Vyronos
Larnaca, 6023
Cyprus
+357.24030130

Technical Contact:
Kyriakos, Kyriako abuse@main-hosting.com
Hostinger International Ltd.
61 Lordou Vyronos
Larnaca, 6023
Cyprus
+357.24030130

Domain servers in listed order:
NS1.000WEBHOST.COM
NS2.000WEBHOST.COM

Registry Status: clientDeleteProhibited
Registry Status: clientRenewProhibited
Registry Status: clientTransferProhibited
Registry Status: clientUpdateProhibited

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