BKDR_BAYROB.P
Mal/Bayrob-A (Sophos)
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It 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
380,416 bytes
EXE
Yes
22 Jan 2016
Arrival Details
This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
It 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%\rmpeumktt\zbze1o5ouv2heujb9jfb.exe
- %System Root%\rmpeumktt\nmtuyjeje.exe
- %System Root%\rmpeumktt\ouxnjybzpkya.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%\rmpeumktt\rzhhdtke0
- %System Root%\rmpeumktt\qiroq1u9wew5
- %System Root%\rmpeumktt\r9du2g9q
- %System Root%\rmpeumktt\rzhhdtke0
(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%\rmpeumktt
- %System Root%\rmpeumktt
(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 registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Event Identity Filtering Profile Remote
Type = "272"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Event Identity Filtering Profile Remote
Start = "2"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Event Identity Filtering Profile Remote
ImagePath = "%System Root%\rmpeumktt\ouxnjybzpkya.exe"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Event Identity Filtering Profile Remote
DisplayName = "Event Identity Filtering Profile Remote"
It adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
Extensible Windows Transfer Human Link-Layer = "%System Root%\rmpeumktt\ouxnjybzpkya.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
Other Details
This backdoor connects to the following possibly malicious URL:
- http://{domain}.net/index.php
NOTES:
It displays a fake error message to inform the user that the file is not executed properly.
The {domain} is generated through concatenating two strings on the following lists:
- answer
- around
- because
- broken
- building
- catch
- clothes
- complete
- degree
- desire
- difficult
- distant
- doctor
- double
- dress
- during
- eearly
- enough
- evening
- expect
- fellow
- foreign
- forward
- future
- gentle
- glass
- govern
- health
- heard
- heaven
- heavy
- indeed
- leader
- length
- machine
- might
- movement
- nature
- necessary
- needle
- notice
- order
- outside
- person
- pleasant
- prepare
- pretty
- proud
- public
- require
- result
- return
- right
- safety
- separate
- still
- store
- strength
- sudden
- various
- welcome
- whether
SOLUTION
9.800
12.292.04
28 Jan 2016
12.293.00
29 Jan 2016
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
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
- Event Identity Filtering Profile Remote
- Event Identity Filtering Profile Remote
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
- Extensible Windows Transfer Human Link-Layer = "%System Root%\rmpeumktt\ouxnjybzpkya.exe"
- Extensible Windows Transfer Human Link-Layer = "%System Root%\rmpeumktt\ouxnjybzpkya.exe"
Step 6
Search and delete this folder
- %Windows%\rmpeumktt
- %System Root%\rmpeumktt
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_BAYROB.P. 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.
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