Trojan.Win32.Sasfis_53c250deb2

Dynamic Analysis

Process activity

The Trojan creates the following process(es):

53c250deb23968e0ec02fe39644a8a70.exe:1708
winlog.exe:2016
CLICKT~1.EXE:1792

The Trojan injects its code into the following process(es):

File activity

The process 53c250deb23968e0ec02fe39644a8a70.exe:1708 makes changes in a file system.

The Trojan creates and/or writes to the following file(s):

%Documents and Settings%\%current user%\Local Settings\Temp\IXP000.TMP\CLICKT~1.EXE (2877 bytes)
%Documents and Settings%\%current user%\Local Settings\Temp\IXP000.TMP\METUSD~1.LNK (1 bytes)

The process winlog.exe:2016 makes changes in a file system.

The Trojan deletes the following file(s):

%Documents and Settings%\%current user%\Application Data\Microsoft\winlog.exe (0 bytes)

The process CLICKT~1.EXE:1792 makes changes in a file system.

The Trojan creates and/or writes to the following file(s):

%Documents and Settings%\%current user%\Application Data\Microsoft\winlog.exe (673 bytes)

Registry activity

The process 53c250deb23968e0ec02fe39644a8a70.exe:1708 makes changes in a system registry.

The Trojan creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "40 5C CD 48 BC CF 5D 66 B1 80 94 21 82 A8 F5 F5"

To automatically run itself each time Windows is booted, the Trojan adds the following link to its file to the system registry autorun key:

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce]
"wextract_cleanup0" = "rundll32.exe %System%\advpack.dll,DelNodeRunDLL32 C:\DOCUME~1\"%CurrentUserName%"\LOCALS~1\Temp\IXP000.TMP\"

The process winlog.exe:2016 makes changes in a system registry.

The Trojan creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "7C 39 0E 55 3A 37 AE CB F5 FA 36 5E F8 29 65 EB"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"AppData" = "%Documents and Settings%\%current user%\Application Data"

To automatically run itself each time Windows is booted, the Trojan adds the following link to its file to the system registry autorun key:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
"winlog.exe" = "%Documents and Settings%\%current user%\Application Data\Microsoft\winlog.exe"

The process CLICKT~1.EXE:1792 makes changes in a system registry.

The Trojan creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "5D 02 80 45 9A A5 D3 14 9C 1B 3B 39 E4 4A 16 DC"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{c155cd73-744b-11e2-8294-806d6172696f}]
"BaseClass" = "Drive"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Cookies" = "%Documents and Settings%\%current user%\Cookies"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Cache" = "%Documents and Settings%\%current user%\Local Settings\Temporary Internet Files"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Common Documents" = "%Documents and Settings%\All Users\Documents"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Desktop" = "%Documents and Settings%\%current user%\Desktop"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{c155cd72-744b-11e2-8294-806d6172696f}]
"BaseClass" = "Drive"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{b98117e8-75ca-11e2-81b2-000c293708fb}]
"BaseClass" = "Drive"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"AppData" = "%Documents and Settings%\%current user%\Application Data"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Common Desktop" = "%Documents and Settings%\All Users\Desktop"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{c155cd75-744b-11e2-8294-806d6172696f}]
"BaseClass" = "Drive"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]
"Personal" = "%Documents and Settings%\%current user%\My Documents"

[HKCU\Software\Microsoft\Windows\ShellNoRoam\MUICache\%Documents and Settings%\%current user%\Application Data\Microsoft]
"winlog.exe" = "winlog"

The Trojan modifies IE settings for security zones to map all urls to the Intranet Zone:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap]
"IntranetName" = "1"

The Trojan modifies IE settings for security zones to map all local web-nodes with no dots which do not refer to any zone to the Intranet Zone:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap]
"UNCAsIntranet" = "1"

The Trojan modifies IE settings for security zones to map all web-nodes that bypassing proxy to the Intranet Zone:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap]
"ProxyBypass" = "1"

Network activity (URLs)

A bot communicates with command and control servers via IRC channel.No activity has been detected.

Rootkit activity

No anomalies have been detected.

Propagation

A worm spreads via removable drives. It writes its executable and creates "autorun.inf" scripts on all removable drives. The autorun script will execute the Trojan's file once a user opens a drive's folder in Windows Explorer.

Removals

Remove it with Ad-Aware

1. Click (here) to download and install Ad-Aware Free Antivirus.
2. Update the definition files.
3. Run a full scan of your computer.

Manual removal*

1. Terminate malicious process(es) (How to End a Process With the Task Manager):

   53c250deb23968e0ec02fe39644a8a70.exe:1708
   winlog.exe:2016
   CLICKT~1.EXE:1792

2. Delete the original Trojan file.
   
3. Delete or disinfect the following files created/modified by the Trojan:

   %Documents and Settings%\%current user%\Local Settings\Temp\IXP000.TMP\CLICKT~1.EXE (2877 bytes)
   %Documents and Settings%\%current user%\Local Settings\Temp\IXP000.TMP\METUSD~1.LNK (1 bytes)
   %Documents and Settings%\%current user%\Application Data\Microsoft\winlog.exe (673 bytes)

4. Delete the following value(s) in the autorun key (How to Work with System Registry):

   [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce]
   "wextract_cleanup0" = "rundll32.exe %System%\advpack.dll,DelNodeRunDLL32 C:\DOCUME~1\"%CurrentUserName%"\LOCALS~1\Temp\IXP000.TMP\"
   
   [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
   "winlog.exe" = "%Documents and Settings%\%current user%\Application Data\Microsoft\winlog.exe"

5. Find and delete all copies of the worm's file together with "autorun.inf" scripts on removable drives.
   

*Manual removal may cause unexpected system behaviour and should be performed at your own risk.

Static Analysis

Network Activity

Map

Strings from Dumps