RANSOM_CRYPWALL.YUYAGA
Trojan.Cryptodefense (Symantec), Ransom:Win32/Crowti!rfn (Microsoft), Ransom.CryptoWall (Malwarebytes),
Windows
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It deletes itself after execution. It is capable of encrypting files in the affected system.
TECHNICAL DETAILS
Arrival Details
This Trojan 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 Trojan drops and executes the following files:
- %Desktop%\HELP_YOUR_FILES.TXT
- %Desktop%\HELP_YOUR_FILES.HTML
- %Desktop%\HELP_YOUR_FILES.PNG
(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop 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.)
It drops the following copies of itself into the affected system:
- %Application Data%\{random characters}\{random characters}.exe
(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random characters} = "%Application Data%\{random characters}\{random characters}.exe"
Other System Modifications
This Trojan modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableSR = "1"
Dropping Routine
This Trojan drops the following files:
- %User Startup%\HELP_YOUR_FILES.TXT
- %User Startup%\HELP_YOUR_FILES.HTML
- %User Startup%\HELP_YOUR_FILES.PNG
- HELP_YOUR_FILES.PNG - drops to all folders where files are encrypted
(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://www.{BLOCKED}e.sh/
- http://blog.{BLOCKED}l.com/NFDayU.php?{random letter}={random values}
- http://{BLOCKED}mission.org/VImTSM.php?{random letter}={random values}
- http://{BLOCKED}fullofcarrots.ch/OIP7rk.php?{random letter}={random values}
- http://{BLOCKED}x.kz/Ov8_qV.php?{random letter}={random values}
- http://{BLOCKED}nk.us/9X2kNr.php?{random letter}={random values}
- http://{BLOCKED}anykaprun.cz/LV6Egb.php?{random letter}={random values}
- http://{BLOCKED}a.com.au/rxo5Zp.php?{random letter}={random values}
- http://{BLOCKED}r-consulting.com/1r432c.php?{random letter}={random values}
- http://{BLOCKED}x.com/VWuyK4.php?{random letter}={random values}
- http://{BLOCKED}nvieira.com.br/6CvxuN.php?{random letter}={random values}
- http://{BLOCKED}orestclocks.org/K6lWQg.php?{random letter}={random values}
- http://{BLOCKED}szen.com/AMx5jI.php?{random letter}={random values}
- http://{BLOCKED}to90210.altervista.org/bJT1VS.php?{random letter}={random values}
- http://{BLOCKED}ay.sk/mE8MKJ.php?{random letter}={random values}
- http://{BLOCKED}eveda.com/i5amQC.php?{random letter}={random values}
- http://{BLOCKED}istictraining.com/c0Mdwh.php?{random letter}={random values}
- http://{BLOCKED}radydrewniane.pl/6Ejz4Y.php?{random letter}={random values}
- http://{BLOCKED}andblings.com/RWH6sC.php?{random letter}={random values}
- http://{BLOCKED}n.ca/IlDH1J.php?{random letter}={random values}
- http://{BLOCKED}nltd.kz/_aP5Qm.php?{random letter}={random values}
- http://{BLOCKED}mode.nl/DaZjW7.php?{random letter}={random values}
- http://{BLOCKED}ance-pc.fr/DzJuMa.php?{random letter}={random values}
- http://{BLOCKED}a-b.pl/WBxm6M.php?{random letter}={random values}
- http://{BLOCKED}gar.com/K1kCOF.php?{random letter}={random values}
- http://{BLOCKED}rd-marine.com/Rd8pPK.php?{random letter}={random values}
- http://{BLOCKED}al-club-boeckels.de/kiCsmO.php?{random letter}={random values}
- http://{BLOCKED}oucomprar.com/cNabw1.php?{random letter}={random values}
- http://{BLOCKED}a.su/wlI0Uy.php?{random letter}={random values}
- http://{BLOCKED}s-krombach.de/F74yDk.php?{random letter}={random values}
- http://{BLOCKED}ballvideobwsl.net/jN3vUi.php?{random letter}={random values}
- http://{BLOCKED}kdental.com/GMu28q.php?{random letter}={random values}
- http://{BLOCKED}ium.altervista.org/cUFD6S.php?{random letter}={random values}
It renames encrypted files using the following names:
- {random characters}.{random characters}
It deletes itself after execution.
It is capable of encrypting files in the affected system.
SOLUTION
NOTES:
Trend customers:
Keep your pattern and scan engine files updated. Trend Micro antivirus software can clean or remove most types of computer threats. Malware, though, such as Trojans, scripts, overwriting viruses and joke programs which are identified as uncleanable, should simply be deleted.
All Internet users:
- Use HouseCall - the Trend Micro online threat scanner to check for malware that may already be on your PC.
- Catch malware/grayware before they affect your PC or network. Secure your Web world with Trend Micro products that offer the best anti-threat and content security solutions for home users, corporate users, and ISPs. Go here for more information on Trend Micro products that fit your needs.
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