Today someone posted about a Ransomware attack on the local chat plaform Jodel (don't judge please, as you know the sketchy corners of the web get you the best samples :D) which instantly peaked my interest. What I got was this email and the two attached files.
The two attached files Applicant Name - Lebenslauf Aktuell.doc.lnk and Applicant Name - Arbeitszeugnisse Aktuell.doc.lnk are made to look like Microsoft Office Documents but are actually just Windows File Shortcuts and can easily be parsed with the LNK Parser @ Google Code. The output looks like this:
The person who provided me with this data was kind enough to also include the ransom note, which is, unlike most ransomware strains out there in the wild wild cyber west, not a txt File but rather a HTML file. It includes links to bitcoin exchanges, a hardcoded wallet address and asks for 0.15038835 BTC as a ransom. Just like the E-Mail it is written in spotless german but without Umlauts (ä,ö,ü). A cleaned sample can be found here Communication with the attacker's server at 126.96.36.199 (hosted at OVH) is done via a php script at the bottom of the ransom note. Since the server was not reachable at the time of analysis I could not take a closer look at neither the script nor the dropped .hta file that is run via the powershell command in the .lnks. The most worrying thing about this sample is the "encryption" though. Every file touched by GermanWiper is overwritten with zeros. A list of file extensions used by the wiper can be found on pastebin. Because of this behaviour the malware was dubbed "GermanWiper" by Michael Gillespie (@Demonslay335). The BleepingComputer Forum post discussing this strain can be found here.
Update: A look at the dropped executable
GermanWiper available @ https://malshare.com/sample.php?action=detail&hash=36ccd442755d482900b57188ae3a89a7 sha256 41364427dee49bf544dcff61a6899b3b7e59852435e4107931e294079a42de7c
As a first step I like to run my samples through "Detect it easy" to get a first look at what to expect. Not a huge discovery, but it interesting none the less that the executable was likely compiled with Visual Studio 2010.
Let's check the entropy of the sample to see if it is packed. Heavy obfuscation is a rare sight for ransomware, but running your executable through a packer or crypter of some sort might avoid detection through already existing signatures and ransom campaigns often ship more than one version of their executable.
A quick test to see how much effort the attackers have put into it is to try to unpack it with upx, but no such luck in this case: I'm not quite sure why, but the attackers set an Amazon Logo as a file icon for the malware. Maybe to lure the victim into clicking on it ?
wiper.exe --SHA1--> 8cd96603cdd2637cf5469aba8ed2b149c35ef699 Arbeitszeugnisse - Lebenslauf - Doris Sammer.zip --SHA1--> 058ad51c8eb86545a5424c0b021235da3bbce1c8 Doris Sammer - Arbeitszeugnisse Aktuell.doc.lnk --SHA1--> 2d8f89693d14b9ea7a056bced983dfc88fe76105 Doris Sammer - Lebenslauf Aktuell.doc.lnk --SHA1--> 77d5224fc02999b04ab79054aad23b0f6213b7eb
applicant.name[at]rasendmail.com applicant.name[at]stadtmailer.com applicant.name[at]nrwmail.com applicant.name[at]mailplatz.com
173.33.106[.]120 moneymaker[.]software expandingdelegation[.]top
Skipped Folders and Filenames
autorun.inf boot.ini bootfont.bin bootsect.bak desktop.ini iconcache.db ntldr ntuser.dat ntuser.dat.log ntuser.ini bootmgr bootnxt thumbs.db Windows recycle.bin mozilla google boot application data appData program files program files (x86) programme programme (x86) programdata perflogs intel msocache System Volume Information
Thanks again to @Demonslay335, @James_inthe_box and all the other researchers who contributed to the anlysis of this threat. This article has also been mentioned in this excellent ZDNet Article, which is quite an honor, thanks :D