RANSOM_DYNACRYPT.A

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

It steals sensitive information such as user names and passwords related to certain games.

It encrypts files with specific file extensions.

Arrival Details

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Ransomware drops the following file(s)/component(s):

• %All Users Profile%\helper.exe
• %All Users Profile%\rec.exe
• %All Users Profile%\cwin.exe <- detected as Ransom_Genasom.R047C0DBA17
• %ProgramData%\helper.exe
• %ProgramData%\rec.exe
• %ProgramData%\cwin.exe <- detected as Ransom_Genasom.R047C0DBA17
• %AppDataLocal%\dyna\cry.exe <- detected as Ransom_DYNACRYPT.THAOEH
• %AppDataLocal%\dyna\kl.exe <- detected as Ransom_Genasom.R002C0DD417
• %AppDataLocal%\dyna\st.exe <- Ransom_DYNACRYPT.THAOEH
• %AppDataLocal%\dyna\res
• %AppDataLocal%\dyna\loot\Keylog\keylog_{date & time}.log <- contains keylog strokes

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It creates the following folders:

• %AppDataLocal%\dyna
• %AppDataLocal%\dyna\loot
• %AppDataLocal%\dyna\loot\Keylog

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Dropping Routine

This Ransomware executes the dropped file. As a result, malicious routines of the dropped file are exhibited on the affected system.

Information Theft

This Ransomware steals sensitive information such as user names and passwords related to the following games:

• Minecraft
• Steam
• TS3

It gathers the following data:

• Keylog strokes
• Screenshots

It attempts to steal stored email credentials from the following:

• Thunderbird
• Skype

It attempts to get stored information such as user names, passwords, and hostnames from the following browsers:

• Chrome
• Firefox

Stolen Information

This Ransomware saves the stolen information in the following file:

• %AppDataLocal%\dyna\loot\Chrome\Cookies
• %AppDataLocal%\dyna\loot\Chrome\History
• %AppDataLocal%\dyna\loot\Firefox\key3.db
• %AppDataLocal%\dyna\loot\Firefox\places.sqlite
• %AppDataLocal%\dyna\loot\Firefox\Keylog\keylog_{date & time}.log
• %AppDataLocal%\dyna\loot\Minecraft
• %AppDataLocal%\dyna\loot\Screenshots
• %AppDataLocal%\dyna\loot\Skype
• %AppDataLocal%\dyna\loot\Steam
• %AppDataLocal%\dyna\loot\Thunderbird
• %AppDataLocal%\dyna\loot\TS3
• %AppDataLocal%\dyna\loot\browserpass.txt

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other Details

This Ransomware does the following:

• It executes the following dropped components using these powershell commands:
  • powershell.exe -win hidden -enc helper.exe
  • powershell.exe -win hidden -enc cwin.exe
  • powershell.exe -win hidden -enc rec.exe
  • powershell.exe -win hidden -enc {encrypted string}
• It displays the following window as a ransom note:
  

Ransomware Routine

This Ransomware encrypts files with the following extensions:

• .jpg
• .jpeg
• .docx
• .doc
• .xlsx
• .xls
• .ppt
• .pdf
• .mp4
• .mp3
• .mov
• .mkv
• .png
• .pst
• .odt
• .avi
• .pptx
• .msg
• .rar
• .mdb
• .zip
• .m4a
• .csv
• .001

It appends the following extension to the file name of the encrypted files:

• .crypt