Backdoor.Win32.Farfli_011141dc3a

Dynamic Analysis

Payload

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

Process activity

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

72185.exe:1244

File activity

The process 72185.exe:1244 makes changes in a file system.

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

%Documents and Settings%\%current user%\Cookies\index.dat (1928 bytes)
%Documents and Settings%\%current user%\Cookies\Current_User@www.ip-adress[1].txt (134 bytes)
%Documents and Settings%\%current user%\Cookies\Current_User@whatismyipaddress[1].txt (206 bytes)

Registry activity

The process 72185.exe:1244 makes changes in a system registry.

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

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache\Paths]
"Directory" = "%Documents and Settings%\%current user%\Local Settings\Temporary Internet Files\Content.IE5"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache\Paths\path4]
"CacheLimit" = "65452"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache\Paths\path4]
"CachePath" = "%Documents and Settings%\%current user%\Local Settings\Temporary Internet Files\Content.IE5\Cache4"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache\Paths\path2]
"CacheLimit" = "65452"

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

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

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache\Paths\path2]
"CachePath" = "%Documents and Settings%\%current user%\Local Settings\Temporary Internet Files\Content.IE5\Cache2"

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

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

[HKLM\System\CurrentControlSet\Hardware Profiles\0001\Software\Microsoft\windows\CurrentVersion\Internet Settings]
"ProxyEnable" = "0"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache\Paths\path1]
"CacheLimit" = "65452"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections]
"SavedLegacySettings" = "3C 00 00 00 13 00 00 00 01 00 00 00 00 00 00 00"

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "52 7B 75 81 0E AC D3 D3 B6 43 AE 08 AF 7E D5 53"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache\Paths\path1]
"CachePath" = "%Documents and Settings%\%current user%\Local Settings\Temporary Internet Files\Content.IE5\Cache1"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache\Paths\path3]
"CacheLimit" = "65452"

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

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

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache\Paths\path3]
"CachePath" = "%Documents and Settings%\%current user%\Local Settings\Temporary Internet Files\Content.IE5\Cache3"

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache\Paths]
"Paths" = "4"

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 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:

[HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
"cuzi" = "%System%\bibapus.exe"

Proxy settings are disabled:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
"ProxyEnable" = "0"

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 deletes the following value(s) in system registry:

[HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
"AutoConfigURL"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
"ProxyServer"

[HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
"ProxyOverride"

Network activity (URLs)

URL	IP
hxxp://www.ipaddress.com/	91.250.85.234
hxxp://www.grokster.com/	72.14.188.13
hxxp://whatismyipaddress.com/	66.80.82.69
hxxp://www.ip-adress.com/	64.34.169.244
hxxp://a1983.g2.akamai.net/
hxxp://static-redirect.zlb.phx.mozilla.net/
hxxp://www.amazon.com/	205.251.242.54
www.mozilla.com	63.245.217.20
ipaddress.com	91.250.85.234
www.weather.com	157.238.74.18

Rootkit activity

No anomalies have been detected.

Propagation

A worm can spread via removable drives. It writes its executable and creates "autorun.inf" scripts on all removable drives. The autorun script will execute the Backdoor'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 the original Backdoor's process (How to End a Process With the Task Manager).
2. Delete the original Backdoor file.
   
3. Delete or disinfect the following files created/modified by the Backdoor:

   %Documents and Settings%\%current user%\Cookies\index.dat (1928 bytes)
   %Documents and Settings%\%current user%\Cookies\Current_User@www.ip-adress[1].txt (134 bytes)
   %Documents and Settings%\%current user%\Cookies\Current_User@whatismyipaddress[1].txt (206 bytes)

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

   [HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
   "cuzi" = "%System%\bibapus.exe"

5. Clean the Temporary Internet Files folder, which may contain infected files (How to clean Temporary Internet Files folder).
   
6. Find and delete all copies of the worm's file together with "autorun.inf" scripts on removable drives.
   
7. 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