Backdoor.Win32.Fynloski_a638594b06

by malwarelabrobot on September 11th, 2013 in Malware Descriptions.

HEUR:Trojan.Win32.Generic (Kaspersky), Packed.Win32.Rebhip.a (v) (VIPRE), Backdoor.Win32.DarkKomet!IK (Emsisoft), Backdoor.Win32.Fynloski.FD, Trojan.Win32.Iconomon.FD, Trojan.Win32.Sasfis.FD, VirTool.Win32.DelfInject.FD, TrojanDownloaderAndromeda.YR, GenericDownloader.YR, BackdoorFynloski.YR, GenericInjector.YR (Lavasoft MAS)
Behaviour: Trojan-Downloader, Trojan, Backdoor, Packed, VirTool


The description has been automatically generated by Lavasoft Malware Analysis System and it may contain incomplete or inaccurate information.

Summary
Technical Details
Removal Recommendations

MD5: a638594b0675abb819d5c4b38c53d258
SHA1: 48d00cd666ec5af60d5d56562712aaddf7e01a6c
SHA256: 3b7ac03c74281d9349890b84a013107a3e31eab72f9cab050040c69a35708026
SSDeep: 12288:PinPV3u7yFQyc0r1K45aeAnMcMSGrcr L9:PinPV3uOFQyJs43FqSzB
Size: 753864 bytes
File type: EXE
Platform: WIN32
Entropy: Not Packed
PEID: MicrosoftVisualCv71EXE, PolyEnE001byLennartHedlund, UPolyXv05_v6
Company: no certificate found
Created at: 2012-06-07 18:59:53


Summary:

Backdoor. Malware that enables a remote control of victim's machine.

Payload

No specific payload has been found.

Process activity

The Backdoor creates the following process(es):

a638594b0675abb819d5c4b38c53d258.exe:1588

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

dllhost.exe:420

File activity

The process a638594b0675abb819d5c4b38c53d258.exe:1588 makes changes in a file system.
The Backdoor creates and/or writes to the following file(s):

%Documents and Settings%\%current user%\Local Settings\Temp\dllhost.exe (5441 bytes)

Registry activity

The process a638594b0675abb819d5c4b38c53d258.exe:1588 makes changes in a system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "A6 CF 4F B3 4C 32 48 A6 2D 10 9E D8 3E 32 8B 7C"

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

[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"

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

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

[HKCU\Software\Microsoft\Windows\ShellNoRoam\MUICache\C:\DOCUME~1\"%CurrentUserName%"\LOCALS~1\Temp]
"dllhost.exe" = "dllhost"

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,C:\DOCUME~1\"%CurrentUserName%"\LOCALS~1\Temp\dllhost.exe"

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"

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 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"

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]
"1111111111111111" = "C:\DOCUME~1\"%CurrentUserName%"\LOCALS~1\Temp\dllhost.exe"

The process dllhost.exe:420 makes changes in a system registry.
The Backdoor creates and/or sets the following values in system registry:

[HKLM\SOFTWARE\Microsoft\Cryptography\RNG]
"Seed" = "E8 FF 36 1A 54 E9 20 03 EA 90 FE E1 16 23 14 6D"

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

[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"

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

Network activity (URLs)

No activity has been detected.

Rootkit activity

No anomalies have been detected.

Propagation


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):

    a638594b0675abb819d5c4b38c53d258.exe:1588

  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\Temp\dllhost.exe (5441 bytes)

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

    [HKCU\Software\Microsoft\Windows\CurrentVersion\Run]
    "1111111111111111" = "C:\DOCUME~1\"%CurrentUserName%"\LOCALS~1\Temp\dllhost.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,C:\DOCUME~1\"%CurrentUserName%"\LOCALS~1\Temp\dllhost.exe"

  6. Reboot the computer.

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