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Microsoft Malware Detection and Removal Tools
Use the following free Microsoft tools to detect and remove this threat:
• Windows Defender – built-in to Windows 10. There’s nothing to buy and nothing to install. No configuration, no subscriptions, and no nagware
• Microsoft Safety Scanner: https://www.microsoft.com/security/scanner/en-us/default.aspx?wt.mc_id=AID618806_EML_5062822
(The Microsoft Safety Scanner is a free downloadable security tool that provides on-demand scanning and helps remove viruses, spyware, and other malicious software. It works with your existing antivirus software. Note: The Microsoft Safety Scanner expires 10 days after being downloaded. To rerun a scan with the latest anti-malware definitions, download and run the Microsoft Safety Scanner again.The Microsoft Safety Scanner is not a replacement for using an antivirus software program that provides ongoing protection.)
Also view :
• Microsoft Security Response Center Blog
• Microsoft Malware Protection Center Blog
• Microsoft Safety and Security Center webpage
We recommend customers that have not yet installed the security update MS17-010 do so as soon as possible. Until you can apply the patch, we recommend two possible workarounds to reduce the attack surface:
• Disable SMBv1 with the steps documented at Microsoft Knowledge Base Article 2696547 (Reboot Required)
• Consider adding a rule on your router or firewall to block incoming SMB traffic on port 445
Windows Defender Antivirus detects this threat as Ransom:Win32/WannaCrypt as of the 1.243.297.0 update.
Enable Windows Defender Antivirus to detect this ransomware.
Windows Defender Antivirus uses cloud-based protection, to help protect you from the latest threats.
Use Office 365 Advanced Threat Protection, which has machine learning capability that blocks dangerous email threats, such as the emails carrying ransomware.
Monitor your network with Windows Defender Advanced Threat Protection, which alerts security operations teams about suspicious activities.
For enterprises, use Device Guard to lock down devices and provide kernel-level virtualization-based security, allowing only trusted applications to run, effectively preventing malware from running.
A ransomware threat does not normally spread so rapidly. Threats like WannaCrypt typically leverage social engineering or emails as primary attack vector, relying on users downloading and executing a malicious payload. However, in this unique case, the ransomware perpetrators incorporated publicly-available exploit code for the patched SMB EternalBlue vulnerability, CVE-2017-0145, which can be triggered by sending a specially crafted packet to a targeted SMBv1 server.
It was fixed in security bulletin MS17-010, released on March 14, 2017.
WannaCrypt’s spreading mechanism is borrowed from well-known public SMB exploits, which armed this regular ransomware with worm-like functionalities, creating an entry vector in machines still unpatched even after the fix had become available.
The exploit code used by WannaCrypt was designed to work only against unpatched Windows 7 and Windows Server 2008 (or earlier OS) systems, so Windows 10 PCs are not affected by this attack.
We haven’t found the exact initial entry vector used by this threat, but there are two scenarios that we believe are highly likely for this ransomware family:
• Arrival through social engineering emails designed to trick users to run the malware and to activate the worm-spreading functionality with the SMB exploit
• Infection through SMB exploit when an unpatched computer can be addressed in other infected machines
The threat arrives as a dropper Trojan that has the following two components:
• Ccomponent that tries to exploit the SMB EternalBlue vulnerability in other computers
• Ransomware known as WannaCrypt
The dropper tries to connect the following domain using the API InternetOpenUrlA():
hxxp://www[.]iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea[.]com
When connection is successful, the threat does not infect the system further with ransomware, nor try to exploit other systems to spread; it simply stops execution. However, when the connection fails, the dropper proceeds to drop the ransomware and creates a service on the system.
Blocking the domain with firewall either at ISP or enterprise network level will just cause the ransomware to continue spreading and encrypting files.
The threat creates a service named mssecsvc2.0, whose function is to exploit the SMB vulnerability in other computers accessible from the infected system:
Service Name: mssecsvc2.0
Service Description: (Microsoft Security Center (2.0) Service)
Service Parameters: “-m security”
When run, WannaCrypt creates the following registry keys:
• HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\\ = “
• HKLM\SOFTWARE\WanaCrypt0r\\wd = “
It changes the wallpaper to a ransom message by modifying the following registry key:
• HKCU\Control Panel\Desktop\Wallpaper: “
It creates the following files in the malware’s working directory:
• 00000000.eky • 00000000.pky
• 00000000.res
• 274901494632976.bat
• @Please_Read_Me@.txt
• @WanaDecryptor@.bmp
• @WanaDecryptor@.exe
• b.wnry
• c.wnry
• f.wnry
• m.vbs
• msg\m_bulgarian.wnry
• msg\m_chinese (simplified).wnry
• msg\m_chinese (traditional).wnry
• msg\m_croatian.wnry
• msg\m_czech.wnry
• msg\m_danish.wnry
• msg\m_dutch.wnry
• msg\m_english.wnry
• msg\m_filipino.wnry
• msg\m_finnish.wnry
• msg\m_french.wnry
• msg\m_german.wnry
• msg\m_greek.wnry
• msg\m_indonesian.wnry
• msg\m_italian.wnry
• msg\m_japanese.wnry
• msg\m_korean.wnry
• msg\m_latvian.wnry
• msg\m_norwegian.wnry
• msg\m_polish.wnry
• msg\m_portuguese.wnry
• msg\m_romanian.wnry
• msg\m_russian.wnry
• msg\m_slovak.wnry
• msg\m_spanish.wnry
• msg\m_swedish.wnry
• msg\m_turkish.wnry
• msg\m_vietnamese.wnry
• r.wnry
• s.wnry
• t.wnry
• TaskData\Tor\libeay32.dll
• TaskData\Tor\libevent-2-0-5.dll
• TaskData\Tor\libevent_core-2-0-5.dll
• TaskData\Tor\libevent_extra-2-0-5.dll
• TaskData\Tor\libgcc_s_sjlj-1.dll
• TaskData\Tor\libssp-0.dll
• TaskData\Tor\ssleay32.dll
• TaskData\Tor\taskhsvc.exe
• TaskData\Tor\tor.exe
• TaskData\Tor\zlib1.dll
• taskdl.exe
• taskse.exe
• u.wnry
WannaCrypt may also create the following files:
• %SystemRoot%\tasksche.exe
• %SystemDrive%\intel\
• %ProgramData%\
It may create a randomly named service that has the following associated ImagePath: “cmd.exe /c “
Then it searches the whole computer for any file with any of the following file name extensions:
.123, .jpeg , .rb , .602 , .jpg , .rtf , .doc , .js , .sch , .3dm , .jsp , .sh , .3ds , .key , .sldm , .3g2 , .lay , .sldm , .3gp , .lay6 , .sldx , .7z , .ldf , .slk , .accdb , .m3u , .sln , .aes , .m4u , .snt , .ai , .max , .sql , .ARC , .mdb , .sqlite3 , .asc , .mdf , .sqlitedb , .asf , .mid , .stc , .asm , .mkv , .std , .asp , .mml , .sti , .avi , .mov , .stw , .backup , .mp3 , .suo , .bak , .mp4 , .svg , .bat , .mpeg , .swf , .bmp , .mpg , .sxc , .brd , .msg , .sxd , .bz2 , .myd , .sxi , .c , .myi , .sxm , .cgm , .nef , .sxw , .class , .odb , .tar , .cmd , .odg , .tbk , .cpp , .odp , .tgz , .crt , .ods , .tif , .cs , .odt , .tiff , .csr , .onetoc2 , .txt , .csv , .ost , .uop , .db , .otg , .uot , .dbf , .otp , .vb , .dch , .ots , .vbs , .der” , .ott , .vcd , .dif , .p12 , .vdi , .dip , .PAQ , .vmdk , .djvu , .pas , .vmx , .docb , .pdf , .vob , .docm , .pem , .vsd , .docx , .pfx , .vsdx , .dot , .php , .wav , .dotm , .pl , .wb2 , .dotx , .png , .wk1 , .dwg , .pot , .wks , .edb , .potm , .wma , .eml , .potx , .wmv , .fla , .ppam , .xlc , .flv , .pps , .xlm , .frm , .ppsm , .xls , .gif , .ppsx , .xlsb , .gpg , .ppt , .xlsm , .gz , .pptm , .xlsx , .h , .pptx , .xlt , .hwp , .ps1 , .xltm , .ibd , .psd , .xltx , .iso , .pst , .xlw , .jar , .rar , .zip , .java , .raw
WannaCrypt encrypts all files it finds and renames them by appending “.WNCRY” to the file name. For example, if a file is named “picture.jpg”, the ransomware encrypts and renames to “picture.jpg.WNCRY”.
This ransomware also creates the file “@Please_Read_Me@.txt” in every folder where files are encrypted. The file contains the same ransom message shown in the replaced wallpaper image. After completing the encryption process, the malware deletes the volume shadow copies by running the following command:
cmd.exe /c vssadmin delete shadows /all /quiet & wmic shadowcopy delete & bcdedit /set {default} bootstatuspolicy ignoreallfailures & bcdedit /set {default} recoveryenabled no & wbadmin delete catalog -quiet
It then replaces the desktop background image with a message and also runs an executable showing a ransom note which indicates a $300 ransom and a timer. The ransomware also demonstrates the decryption capability by allowing the user to decrypt a few random files, free of charge. It then quickly reminds the user to pay the ransom to decrypt all the remaining files. The worm functionality attempts to infect unpatched Windows machines in the local network. At the same time, it also executes massive scanning on Internet IP addresses to find and infects other vulnerable computers. This activity results in large SMB traffic from the infected host, which normally can be observed by SecOps personnel.
Once a vulnerable machine is found and infected, it becomes the next hop to infect other machines. The vicious infection cycle continues as the scanning routing discovers unpatched computers. When it successfully infects a vulnerable computer, the malware runs kernel-level shellcode which seems to have been copied from the public backdoor known as DOUBLEPULSAR, but with certain adjustments to drop and execute the ransomware dropper payload, both for x86 and x64 systems.
