Send us feedback
We're gradually updating threat actor names in our reports to align with the new weather-themed taxonomy. Learn about Microsoft threat actor names
Ransom:MSIL/Samas.A
Aliases: No associated aliases
Summary
Windows Defender Antivirus detects and removes this threat.
This ransomware family encrypts the files on your PC. It shows you a message that says you must pay for decryption software to get access to your files again.
You can read more about this type of threat on our ransomware page.
There is no one-size-fits-all response if you have been victimized by ransomware. There is no guarantee that paying the ransom will give you access to your files.
If you've already paid, see our ransomware page for help on what to do now.
Run antivirus or antimalware software
Use the following free Microsoft software to detect and remove this threat:
- Microsoft Defender Antivirus for Windows 10 and Windows 8.1, or Microsoft Security Essentials for Windows 7 and Windows Vista
- Microsoft Safety Scanner
You should also run a full scan. A full scan might find other hidden malware.
Advanced troubleshooting
To restore your PC, you might need to download and run Windows Defender Offline. See our advanced troubleshooting page for more help.
Get more help
You can also visit our advanced troubleshooting page or search the Microsoft virus and malware community for more help.
If you’re using Windows XP, see our Windows XP end of support page.
Threat behavior
Installation
This malware is dropped in the <system folder> as samsam.exe with a key <ComputerName>_PublicKey.xml which is used to encrypt the file in the system.
Payload
Encrypts your files
This malware searches for files in all folders with the following extensions and then encrypts them:
.3dm |
.crw |
.iiq |
.otp |
.sdf |
.3ds |
.cs |
.incpas |
.ots |
.sldm |
.3fr |
.csh |
.indd |
.ott |
.sldx |
.3g2 |
.csl |
.jar |
.p12 |
.sql |
.3gp |
.csv |
.java |
.p7b |
.sqlite |
.3pr |
.dac |
.jpe |
.p7c |
.sqlite3 |
.7z |
.db |
.jpeg |
.pab |
.sqlitedb |
.ab4 |
.db3 |
.jpg |
.pages |
.sr2 |
.accdb |
.dbf |
.jsp |
.pas |
.srf |
.accde |
.db-journal |
.kbx |
.pat |
.srt |
.accdr |
.dbx |
.kc2 |
.pbl |
.srw |
.accdt |
.dc2 |
.kdbx |
.pcd |
.st4 |
.ach |
.dcr |
.kdc |
.pct |
.st5 |
.acr |
.dcs |
.key |
.pdb |
.st6 |
.act |
.ddd |
.kpdx |
.pdd |
.st7 |
.adb |
.ddoc |
.lua |
|
.st8 |
.ads |
.ddrw |
.m |
.pef |
.std |
.agdl |
.dds |
.m4v |
.pem |
.sti |
.ai |
.der |
.max |
.pfx |
.stw |
.ait |
.des |
.mdb |
.php |
.stx |
.al |
.design |
.mdc |
.php5 |
.svg |
.apj |
.dgc |
.mdf |
.phtml |
.swf |
.arw |
.djvu |
.mef |
.pl |
.sxc |
.asf |
.dng |
.mfw |
.plc |
.sxd |
.asm |
.doc |
.mmw |
.png |
.sxg |
.asp |
.docm |
.moneywell |
.pot |
.sxi |
.aspx |
.docx |
.mos |
.potm |
.sxi |
.asx |
.dot |
.mov |
.potx |
.sxm |
.avi |
.dotm |
.mp3 |
.ppam |
.sxw |
.awg |
.dotx |
.mp4 |
.pps |
.tex |
.back |
.drf |
.mpg |
.ppsm |
.tga |
.backup |
.drw |
.mrw |
.ppsx |
.thm |
.backupdb |
.dtd |
.msg |
.ppt |
.tib |
.bak |
.dwg |
.myd |
.pptm |
.tif |
.bank |
.dxb |
.nd |
.pptx |
.tlg |
.bay |
.dxf |
.ndd |
.prf |
.txt |
.bdb |
.dxg |
.nef |
.ps |
.vob |
.bgt |
.eml |
.nk2 |
.psafe3 |
.wallet |
.bik |
.eps |
.nop |
.psd |
.war |
.bkf |
.erbsql |
.nrw |
.pspimage |
.wav |
.bkp |
.erf |
.ns2 |
.pst |
.wb2 |
.blend |
.exf |
.ns3 |
.ptx |
.wmv |
.bpw |
.fdb |
.ns4 |
.py |
.wpd |
.c |
.ffd |
.nsd |
.qba |
.wps |
.cdf |
.fff |
.nsf |
.qbb |
.x11 |
.cdr |
.fh |
.nsg |
.qbm |
.x3f |
.cdr3 |
.fhd |
.nsh |
.qbr |
.xis |
.cdr4 |
.fla |
.nwb |
.qbw |
.xla |
.cdr5 |
.flac |
.nx2 |
.qbx |
.xlam |
.cdr6 |
.flv |
.nxl |
.qby |
.xlk |
.cdrw |
.fmb |
.nyf |
.r3d |
.xlm |
.cdx |
.fpx |
.oab |
.raf |
.xlr |
.ce1 |
.fxg |
.obj |
.rar |
.xls |
.ce2 |
.gray |
.odb |
.rat |
.xlsb |
.cer |
.grey |
.odc |
.raw |
.xlsm |
.cfp |
.gry |
.odf |
.rdb |
.xlsx |
.cgm |
.h |
.odg |
.rm |
.xlt |
.cib |
.hbk |
.odm |
.rtf |
.xltm |
.class |
.hpp |
.odp |
.rw2 |
.xltx |
.cls |
.htm |
.ods |
.rwl |
.xlw |
.cmt |
.html |
.odt |
.rwz |
.xml |
.cpi |
.ibank |
.oil |
.s3db |
.ycbcra |
.cpp |
.ibd |
.orf |
.sas7bdat |
.yuv |
.cr2 |
.ibz |
.ost |
.say |
.zip |
.craw |
.idx |
.otg |
.sd0 |
|
.crt |
.iif |
.oth |
.sda |
It renames the encrypted files by adding "encrypted.RSA" to their extension, for example:
- Help.txt-> Help.txt.encrypted.RSA
It then creates the file HELP_DECRYPT_YOUR_FILES.html in the root folder of the encrypted files as well as in the %Desktop% folder.
This html file contains the instructions on how to decrypt the files by asking you to pay a fee:
After encrypting your files, this malware automatically deletes itself to remove its traces in the system.
Analysis Ric Robielos
Prevention
The following could indicate that you have this threat on your PC:
- You see this ransom screen: