BKDR_BAYROB.L
a variant of Win32/Bayrob.W trojan (ESET),
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
Downloaded from the Internet
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
TECHNICAL DETAILS
397824 bytes
EXE
Yes
15 May 2015
Connects to URLs/IPs, Downloads files, Displays message/message boxes
Arrival Details
This backdoor 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 backdoor drops the following copies of itself into the affected system and executes them:
- %System Root%\bmzrqaggtbn\gacnvrmzvff.exe
- %System Root%\bmzrqaggtbn\oh{random variables}whraonjd.exe
- %System Root%\bmzrqaggtbn\zgoqyihu.exe
(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)
It drops the following files:
- %Windows%\bmzrqaggtbn\p4frr7idzz
- %System Root%\bmzrqaggtbn\p4frr7idzz
- %System Root%\bmzrqaggtbn\gymijybd
- %System Root%\bmzrqaggtbn\yxynam3txw
(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)
It creates the following folders:
- %Windows%\bmzrqaggtbn\
- %System Root%\bmzrqaggtbn\
(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
Time Resource Alerts Storage Filtering Tiles = "%System Root%\bmzrqaggtbn\gacnvrmzvff.exe"
It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Proxy Session Routing Manager
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Proxy Session Routing Manager\Security
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Proxy Session Routing Manager\Enum
Other System Modifications
This backdoor adds the following registry entries:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Proxy Session Routing Manager
Type = "110"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Proxy Session Routing Manager
Start = "2"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Proxy Session Routing Manager
ErrorControl = "0"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Proxy Session Routing Manager
ImagePath = "%System Root%\bmzrqaggtbn\gacnvrmzvff.exe"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Proxy Session Routing Manager
DisplayName = "Proxy Session Routing Manager"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Proxy Session Routing Manager
ObjectName = "LocalSystem"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Proxy Session Routing Manager\Security
Security = "(value)"
Download Routine
This backdoor accesses the following websites to download files:
- http:\{hostname}.net\index.php
NOTES:
This backdoor displays a fake error message to inform the user that the file was not executed properly.
The {hostname} by concatenating two of the following values:
- action
- alone
- amount
- around
- because
- become
- bicycle
- bridge
- brought
- building
- chief
- children
- cigarette
- class
- college
- company
- cover
- desire
- direct
- doctor
- dollar
- double
- either
- enough
- evening
- except
- expect
- family
- fellow
- figure
- finger
- foreign
- further
- glossary
- govern
- history
- kitchen
- likely
- machine
- method
- middle
- might
- morning
- movement
- nature
- needle
- often
- outside
- person
- picture
- prepare
- present
- pretty
- probable
- rather
- realize
- result
- right
- round
- shore
- shoulder
- still
- store
- strange
- strength
- strings
- student
- sudden
- thick
- think
- though
- twelve
- until
- wagon
- weather
- welcome
- whether
- whose
- without
- worth
- written
SOLUTION
9.750
11.670.05
15 May 2015
11.671.00
16 May 2015
Step 1
Before doing any scans, Windows XP, Windows Vista, and Windows 7 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
Step 4
Search and delete this folder
- %Windows%\bmzrqaggtbn\
- %System Root%\bmzrqaggtbn\
Step 5
Delete this registry value
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\Run
- Time Resource Alerts Storage Filtering Tiles = "%System Root%\bmzrqaggtbn\gacnvrmzvff.exe"
- Time Resource Alerts Storage Filtering Tiles = "%System Root%\bmzrqaggtbn\gacnvrmzvff.exe"
Step 6
Delete this registry key
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\CurrentControlSet\Services
- Proxy Session Routing Manager
- Proxy Session Routing Manager
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_BAYROB.L. 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.
Did this description help? Tell us how we did.