Analysis by: Rika Joi Gregorio
 Modified by: Carlos Villegas Madrid
ALIASES:

Worm:W32/Downadup.AI (FSECURE)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Propagates via software vulnerabilities, Dropped by other malware, Downloaded from the Internet

This Worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It takes advantage of certain vulnerabilities.

  TECHNICAL DETAILS

File Size: 161,547 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 31 Aug 2017
Payload: Connects to URLs/IPs, Drops files, Modifies system registry

Arrival Details

This Worm 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 Worm drops the following files:

  • {Drive}\autorun.inf

It drops the following copies of itself into the affected system:

  • {Drive}\RECYCLER\{SID}\{Random characters}.{Random extension}
  • \{Server host name}\ADMIN$\System32\{Random characters}.{Random extension}
  • %Application Data%\{Random characters}.dll
  • %Program Files%\Internet Explorer\{Random characters}.dll
  • %Program Files%\Movie Maker\{Random characters}.dll
  • %System%\{Random characters}.dll
  • %System%\{Random characters}.tmp
  • %Temp%\{Random characters}.dll
  • %Temp%\{Random characters}.tmp

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %Temp% is the Windows temporary folder, where it usually is C:\Windows\Temp on all Windows operating system versions.)

It adds the following processes:

  • netsh interface tcp set global autotuning=disabled (Disables TCP/IP auto-tuning if the sample is running on Windows Vista)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • {Random characters}
  • Global\{Random characters based on computer name}-7

It injects codes into the following process(es):

  • svchost.exe
  • explorer.exe
  • services.exe (If the sample is running on Windows 2000)

Autostart Technique

This Worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SYSTEM\{Control set}\
services\{Random characters}
DisplayName = {Random string}

HKEY_LOCAL_MACHINE\SYSTEM\{Control set}\
services\{Random characters}
Start = 2

HKEY_LOCAL_MACHINE\SYSTEM\{Control set}\
services\{Random characters}
ImagePath = %SystemRoot%\system32\svchost.exe -k netsvcs

HKEY_LOCAL_MACHINE\SYSTEM\{Control set}\
services\{Random characters}\Parameters
ServiceDll = %System%\{Random characters}.dll

HKEY_CURRENT_USERSoftware\Microsoft\Windows\
CurrentVersion\Run
{Random characters} = rundll32.exe {Malware file name and path}, {Parameter}

Other System Modifications

This Worm adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Applets
dl = 0

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Applets
ds = 0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets
dl = 0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets
ds = 0

It modifies the following registry entries to hide files with Hidden attributes:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = 0

Other Details

This Worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\{Control set}\
services\{Random characters}

It connects to the following URL(s) to get the affected system's IP address:

  • http://www.{BLOCKED}p.org
  • http://www.{BLOCKED}yipaddress.com
  • http://www.{BLOCKED}myip.org
  • http://{BLOCKED}.dyndns.org

It connects to the following time servers to determine the current date:

  • ask.com
  • yahoo.com
  • google.com
  • baidu.com
  • myspace.com
  • msn.com
  • ebay.com
  • cnn.com
  • aol.com

It does the following:

  • It disables the windows defender and delete registry entries pertaining to Windows Defender auto start mechanism.
  • It patches %System%\drivers\tcpip.sys after loading it in the memory to spread more rapidly across a network.
  • It generates a set of domains based on the returned system time. If a domain is active among the generated domains, it formats its response to http://{Address}/search?q={Number} to download files.
  • It creates an HTTP server with the format http://{IP address}:{Random port} to propagate over the Internet.
  • It deletes all system restore points to disable user from reverting back to a previous system restore point.
  • It hooks the following API to avoid the exploitation of the used vulnerability:
    • NetpwPathCanonicalize
  • It hooks the following API to block user access to certain sites:
    • DNS_Query_A
    • DNS_Query_UTF8
    • DNS_Query_W
    • Query_Main
    • sendto
  • It modifies the following registry entries to execute its copy:
    • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Svchost
      • netsvcs = {Old data}, {Appended created malicious service registry entry}
  • It adds the following registry entries to spread more rapidly across a network:
    • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
      • TcpNumConnections = 0x00fffffe
  • It creates a scheduled task with the following command on a remote server with brute-forced credentials to execute its copy:
    • rundll32.exe {Random characters}.{Random extension}, {Parameter}
  • It creates the following named pipe to allow external hosts or local processes to connect and upload a binary:
    • \.\pipe\System_{Computer name}7
  • It blocks infected systems from visiting certain sites containing the following strings:
    • ccert
    • sans
    • bit9
    • vet
    • avg
    • avp
    • ca
    • nai
    • windowsupdate
    • wilderssecurity
    • threatexpert
    • castlecops
    • spamhaus
    • cpsecure
    • arcabit
    • emsisoft
    • sunbelt
    • securecomputing
    • rising
    • prevx
    • pctools
    • norman
    • k7computing
    • ikarus
    • hauri
    • hacksoft
    • gdata
    • fortinet
    • ewido
    • clamav
    • comodo
    • quickheal
    • avira
    • avast
    • esafe
    • ahnlab
    • centralcommand
    • drweb
    • grisoft
    • eset
    • nod32
    • f-prot
    • jotti
    • kaspersky
    • f-secure
    • computerassociates
    • networkassociates
    • etrust
    • panda
    • sophos
    • trendmicro
    • mcafee
    • norton
    • symantec
    • microsoft
    • defender
    • rootkit
    • malware
    • spyware
    • virus
  • It uses the following strings to generate service registry entry name:
    • Boot
    • Center
    • Config
    • Driver
    • Helper
    • Image
    • Installer
    • Manager
    • Microsoft
    • Monitor
    • Network
    • Security
    • Server
    • Shell
    • Support
    • System
    • Task
    • Time
    • Universal
    • Update
    • Windows
  • It uses the following credentials to brute-force vulnerable systems:
    • 99999999
    • 9999999
    • 999999
    • 99999
    • 9999
    • 999
    • 99
    • 9
    • 88888888
    • 8888888
    • 888888
    • 88888
    • 8888
    • 888
    • 88
    • 8
    • 77777777
    • 7777777
    • 777777
    • 77777
    • 7777
    • 777
    • 77
    • 7
    • 66666666
    • 6666666
    • 666666
    • 66666
    • 6666
    • 666
    • 66
    • 6
    • 55555555
    • 5555555
    • 555555
    • 55555
    • 5555
    • 555
    • 55
    • 5
    • 44444444
    • 4444444
    • 444444
    • 44444
    • 4444
    • 444
    • 44
    • 4
    • 33333333
    • 3333333
    • 333333
    • 33333
    • 3333
    • 333
    • 33
    • 3
    • 22222222
    • 2222222
    • 222222
    • 22222
    • 2222
    • 222
    • 22
    • 2
    • 11111111
    • 1111111
    • 111111
    • 11111
    • 1111
    • 111
    • 11
    • 1
    • 00000000
    • 0000000
    • 00000
    • 0000
    • 000
    • 00
    • 0987654321
    • 987654321
    • 87654321
    • 7654321
    • 654321
    • 54321
    • 4321
    • 321
    • 21
    • 12
    • fuck
    • zzzzz
    • zzzz
    • zzz
    • xxxxx
    • xxxx
    • xxx
    • qqqqq
    • qqqq
    • qqq
    • aaaaa
    • aaaa
    • aaa
    • sql
    • file
    • web
    • foo
    • job
    • home
    • work
    • intranet
    • controller
    • killer
    • games
    • private
    • market
    • coffee
    • cookie
    • forever
    • freedom
    • student
    • account
    • academia
    • files
    • windows
    • monitor
    • unknown
    • anything
    • letitbe
    • letmein
    • domain
    • access
    • money
    • campus
    • explorer
    • exchange
    • customer
    • cluster
    • nobody
    • codeword
    • codename
    • changeme
    • desktop
    • security
    • secure
    • public
    • system
    • shadow
    • office
    • supervisor
    • superuser
    • share
    • super
    • secret
    • server
    • computer
    • owner
    • backup
    • database
    • lotus
    • oracle
    • business
    • manager
    • temporary
    • ihavenopass
    • nothing
    • nopassword
    • nopass
    • Internet
    • internet
    • example
    • sample
    • love123
    • boss123
    • work123
    • home123
    • mypc123
    • temp123
    • test123
    • qwe123
    • abc123
    • pw123
    • root123
    • pass123
    • pass12
    • pass1
    • admin123
    • admin12
    • admin1
    • password123
    • password12
    • password1
    • default
    • foobar
    • foofoo
    • temptemp
    • temp
    • testtest
    • test
    • rootroot
    • root
    • adminadmin
    • mypassword
    • mypass
    • pass
    • Login
    • login
    • Password
    • password
    • passwd
    • zxcvbn
    • zxcvb
    • zxccxz
    • zxcxz
    • qazwsxedc
    • qazwsx
    • q1w2e3
    • qweasdzxc
    • asdfgh
    • asdzxc
    • asddsa
    • asdsa
    • qweasd
    • qwerty
    • qweewq
    • qwewq
    • nimda
    • administrator
    • Admin
    • admin
    • a1b2c3
    • 1q2w3e
    • 1234qwer
    • 1234abcd
    • 123asd
    • 123qwe
    • 123abc
    • 123321
    • 12321
    • 123123
    • 1234567890
    • 123456789
    • 12345678
    • 1234567
    • 123456
    • 12345
    • 1234
    • 123

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It takes advantage of the following vulnerabilities:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 10.240.02
FIRST VSAPI PATTERN DATE: 26 Aug 2013
VSAPI OPR PATTERN File: 10.241.00
VSAPI OPR PATTERN Date: 27 Aug 2013

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
    • TcpNumConnections=0x00fffffe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Applets
    • dl=0
    • ds=0
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets
    • dl=0
    • ds=0
  • In HKEY_CURRENT_USERSoftware\Microsoft\Windows\CurrentVersion\Run
    • {Random characters}=rundll32.exe {Malware file name and path}, {Parameter}

Step 5

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\{Control set}\services
    • {Random characters}

Step 6

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • CheckedValue=0 (Change to 1)
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Svchost
    • netsvcs={Old data}, {Appended created malicious service registry entry} (Change to {Old data})

Step 7

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • {Drive}\autorun.inf
  • {Drive}\RECYCLER\{SID}\{Random characters}.{Random extension}
  • \{Server host name}\ADMIN$\System32\{Random characters}.{Random extension}
  • %Application Data%\{Random characters}.dll
  • %Program Files%\Internet Explorer\{Random characters}.dll
  • %Program Files%\Movie Maker\{Random characters}.dll
  • %System%\{Random characters}.dll
  • %System%\{Random characters}.tmp
  • %Temp%\{Random characters}.dll
  • %Temp%\{Random characters}.tmp

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_DOWNAD.FR. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 9

Download and apply this security patch Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.

Step 10

Scan your computer with your Trend Micro product to delete files detected as WORM_DOWNAD.FR. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check the following Trend Micro Support pages for more information:


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