Backdoor.Win32.Fynloski_9c53cb72f4

Dynamic Analysis

Payload

Behaviour	Description
IRCBot	A bot can communicate with command and control servers via IRC channel.

Process activity

The Backdoor creates the following process(es):

9c53cb72f43184232a32715b1bc6f092.exe:624

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

vbc.exe:1612

File activity

The process 9c53cb72f43184232a32715b1bc6f092.exe:624 makes changes in a file system.

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

%Documents and Settings%\%current user%\Local Settings\Application Data\svchost.exe (134 bytes)
%Documents and Settings%\%current user%\Local Settings\Application Data\JavaUpdate.exe (1862 bytes)

The process vbc.exe:1612 makes changes in a file system.

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

%Documents and Settings%\%current user%\My Documents\MSDCSC\msdcsc.exe (7547 bytes)

Registry activity

The process 9c53cb72f43184232a32715b1bc6f092.exe:624 makes changes in a system registry.

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

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "27 E1 7C 32 61 B0 EE F5 48 52 D7 6B DF DC 4B 09"

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

[HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MountPoints2\{5c14c4f6-74da-11e2-81b0-000c29ec7fc5}]
"BaseClass" = "Drive"

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

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

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

[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\{c155cd75-744b-11e2-8294-806d6172696f}]
"BaseClass" = "Drive"

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

[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\Shell Folders]
"Cache" = "%Documents and Settings%\%current user%\Local Settings\Temporary Internet Files"

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

The Backdoor 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 Backdoor 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 Backdoor 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"

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

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

The process vbc.exe:1612 makes changes in a system registry.

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

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "D7 14 6C 8F DC 40 49 51 68 D3 1A C2 4F C2 0B DC"

The Backdoor adds the reference to itself to be executed when a user logs on:

[HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
"UserInit" = "%System%\userinit.exe,%Documents and Settings%\%current user%\My Documents\MSDCSC\msdcsc.exe"

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

[HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
"MicroUpdate" = "%Documents and Settings%\%current user%\My Documents\MSDCSC\msdcsc.exe"

Network activity (URLs)

No activity has been detected.

Rootkit activity

No anomalies have been detected.

Propagation

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):

   9c53cb72f43184232a32715b1bc6f092.exe:624
   

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

   %Documents and Settings%\%current user%\Local Settings\Application Data\svchost.exe (134 bytes)
   %Documents and Settings%\%current user%\Local Settings\Application Data\JavaUpdate.exe (1862 bytes)
   %Documents and Settings%\%current user%\My Documents\MSDCSC\msdcsc.exe (7547 bytes)

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

   [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
   "JavaUpdate" = "%Documents and Settings%\%current user%\Local Settings\Application Data\JavaUpdate.exe"
   
   [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
   "MicroUpdate" = "%Documents and Settings%\%current user%\My Documents\MSDCSC\msdcsc.exe"

5. Remove the references to the Backdoor by modifying the following registry value(s) (How to Work with System Registry):

   [HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]
   "UserInit" = "%System%\userinit.exe,%Documents and Settings%\%current user%\My Documents\MSDCSC\msdcsc.exe"

6. Reboot the computer.
   

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

Static Analysis

Network Activity

Map

Strings from Dumps