Ransom.Win32.AVADDON.YJAF-A

Publish Date: 18 июня 2020

Author: Mohammed Malubay

Modified By:: Alyssa Christelle Ramos

Ransom:Win32/Avaddon.PA!MTB(MICROSOFT); Win32/Filecoder.Avaddon.A trojan(NOD32);

PLATFORM:

Windows

OVER ALL RISK RATING:

DAMAGE POTENTIAL:

DISTRIBUTION POTENTIAL:

REPORTED INFECTION:

INFORMATION EXPOSURE

Low

Medium

High

Critical

Threat Type:
Ransomware
Destructiveness:
No
Encrypted:
Yes
In the wild:
Yes

OVERVIEW

INFECTION CHANNEL: Downloaded from the Internet

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be downloaded by other malware/grayware from remote sites.

It encrypts files found in specific folders. It drops files as ransom note. It avoids encrypting files with the following file extensions.

TECHNICAL DETAILS

File size: 1,078,784 bytes

File type: EXE

Memory resident: Yes

INITIAL SAMPLES RECEIVED DATE: 09 июня 2020

PAYLOAD: Connects to URLs/IPs, Disables services, Encrypts files, Terminates processes

Arrival Details

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

It may be downloaded by the following malware/grayware from remote sites:

Trojan.JS.AVADDON.YJAF-A

Installation

This Ransomware drops the following copies of itself into the affected system:

%Application Data%\{malware filename}.exe

(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).)

It adds the following processes:

wmic.exe SHADOWCOPY /nointeractive
wbadmin DELETE SYSTEMSTATEBACKUP
wbadmin DELETE SYSTEMSTATEBACKUP -deleteOldest
bcdedit.exe /set {default} recoveryenabled No
bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures
vssadmin.exe Delete Shadows /All /Quiet

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
update = %Application Data%\{malware filename}.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
update = %Application Data%\{malware filename}.exe

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
Owner = {HEX VALUES}

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
SessionHash = {HEX VALUES}

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
Sequence = {VALUE}

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
RegFiles0000 = {Target File Name}

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
RegFilesHash = {Hex Values}

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = 0

(Note: The default value data of the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLinkedConnections = 1

(Note: The default value data of the said registry entry is None.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
ConsentPromptBehaviorAdmin = 0

(Note: The default value data of the said registry entry is 5.)

It changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Profile%\bckgrd.bmp

It sets the system's desktop wallpaper to the following image:

Process Termination

This Ransomware terminates the following services if found on the affected system:

ccEvtMgr
ccSetMgr
Culserver
dbeng8
dbsrv12
DefWatch
Intuit.QuickBooks.FCS
msmdsrv
QBCFMonitorService
QBIDPService
RTVscan
sqladhlp
SQLADHLP
sqlagent
sqlbrowser
sqlservr
sqlwriter
tomcat6
VMAuthdService
VMnetDHCP
VMUSBArbService
vmware-converter
VMwareHostd
vmware-usbarbitator64

It terminates the following processes if found running in the affected system's memory:

360doctor.exe
360se.exe
axlbridge.exe
BCFMonitorService.exe
Culture.exe
Defwatch.exe
fdhost.exe
fdlauncher.exe
GDscan.exe
httpd.exe
java.exe
MsDtSrvr.exe
QBDBMgr.exe
QBIDPService.exe
QBIDPService.exe
qbupdate.exe
QBW32.exe
RAgui.exe
RTVscan.exe
sqlbrowser.exe
sqlservr.exe
supervise.exe
tomcat6.exe
wdswfsafe.exe
winword.exe
wxServer.exe
wxServerView.exe

Other Details

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0001

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0002

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

api.myip.com

It does the following:

Terminates itself if Windows Locale ID is equal to the following:
- 419 = Russian
- 422 = Ukrainian
Terminates itself if machine is set to the following keyboard layout language:
- 419 = Russian
- 485 = Yakut(Russia)
- 444 = Tatar
- 422 = Ukrainian
This ransomware affects all existing drives in the system

It adds the following scheduled tasks:

Task Name: update
Task to run: %Application Data%\{Malware Filename}.exe
Trigger: At {install time} every day - After triggered, repeat every 10 minutes indefinitely

Ransomware Routine

This Ransomware encrypts files found in the following folders:

Program Files\Microsoft\Exchange Server
Program Files (x86)\Microsoft\Exchange Server
Program Files\Microsoft SQL Server
Program Files (x86)\Microsoft SQL Server

It avoids encrypting files with the following strings in their file name:

bckgrd.bmp

It avoids encrypting files with the following strings in their file path:

Windows
Program Files
Users\All Users
%User Temp%
Program Files (x86)
%User Profile%\AppData
ProgramData
Tor Browser

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It appends the following extension to the file name of the encrypted files:

.avdn

It drops the following file(s) as ransom note:

{Encrypted Directory}\{random numbers}-readme.html

It avoids encrypting files with the following file extensions:

.bin
.dat
.dll
.drv
.exe
.ini
.lnk
.prf
.rdp
.swp
.sys
.avdn

SOLUTION

Minimum scan engine: 9.850

First VSAPI Pattern File: 15.924.02

First VSAPI Pattern Release Date: 11 июня 2020

VSAPI OPR PATTERN-VERSION: 15.925.00

VSAPI OPR PATTERN DATE: 12 июня 2020

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

Troj.Win32.TRX.XXPE50FFF036

Step 2

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 3

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 4

Restart in Safe Mode

[ learnMore ]

Step 5

Delete this registry key

[ learnMore ]

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_CURRENT_USER\Software\Microsoft
- RestartManager\Session0000
In HKEY_CURRENT_USER\Software\Microsoft
- RestartManager\Session0001
In HKEY_CURRENT_USER\Software\Microsoft
- RestartManager\Session0002

Step 6

Delete this registry value

[ learnMore ]

In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- EnableLinkedConnections = 1
In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- update = %Application Data%\{malware filename}.exe
In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- update = %Application Data%\{malware filename}.exe

Step 7

Restore these modified registry values

[ learnMore ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- From: EnableLUA = 0
  To: EnableLUA = 1
In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- From: ConsentPromptBehaviorAdmin = 0
  To: ConsentPromptBehaviorAdmin = 5

Step 8

Search and delete these files

[ learnMore ]

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.

%Application Data%\{malware filename}.exe
{Encrypted Directory}\{random numbers}-readme.html

Step 9

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:

update = %Application Data%\{Malware filename}.exe

For Windows 2000, Windows XP, and Windows Server 2003:

Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
System Tools>Scheduled Tasks.
Locate each {Task Name} values listed above in the Name column.
Right-click on the said file(s) with the aforementioned value.
Click on Properties. In the Run field, check for the listed {Task to be run}.
If the strings match the list above, delete the task.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

Open the Windows Task Scheduler. To do this:
• On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
• On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
In the left panel, click Task Scheduler Library.
In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
If the said string is found, delete the task.

Step 10

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.AVADDON.YJAF-A. 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 11

Enabling Volume Shadow Service

Run the command prompt (cmd.exe) as administrator.
Enable Volume Shadow Service by typing the following command:
net start vss

Step 12

Enabling Windows Error Recovery

Run the command prompt (cmd.exe) as administrator.
Enable Windows Error Recovery Screen on Startup by typing the following command:
bcdedit /set {default} bootstatuspolicy displayallfailures

Step 13

Restore encrypted files from backup.

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