BKDR_POSTBOT.ER
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Backdoor
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
It did not exhibit information theft routines during testing. It has no rootkit capabilities.
It executes commands from a remote malicious user, effectively compromising the affected system.
This backdoor may be downloaded by other malware/grayware/spyware from remote sites. It may be unknowingly downloaded by a user while visiting malicious websites.
TECHNICAL DETAILS
35,840 bytes
PE
Yes
25 Dec 2010
Compromises system security, Connects to URLs/Ips
Arrival Details
This backdoor may be downloaded by other malware/grayware/spyware from remote sites.
It may be unknowingly downloaded by a user while visiting malicious websites.
Installation
This backdoor adds the following mutexes to ensure that only one of its copies runs at any one time:
- siueu2dowg
Other System Modifications
This backdoor adds the following registry keys:
HKEY_LOCAL_MACHINE\tmp123
It adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer
MMID = {hex values}
Download Routine
This backdoor saves the files it downloads using the following names:
- %System%\svch0st.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
NOTES:
Backdoor Routine
This Backdoor executes the following commands from a remote malicious user:
- Connects to another URL
- Downloads other files
- Executes a file named %System%\svch0st.exe with the /u parameter
- Execute a file named %System%\svch0st.exe with the /g parameter
- Executes arbitrary CMD.EXE shell commands
- Enumerates all drives and acquires drive information
- Creates a new directory
- Creates a process
- Terminates processes
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- {host name}\{random alphanumeric characters}{hard-coded string}.php
The host name can be any of the following:
- newz.{BLOCKED}eck.org
- {BLOCKED}te.nameserver.ns2.name
The hard-coded string can be any of the following:
- lkwoeg.php
- qowgmh.php
- nlwghg.php
- adowhg.php
- zjfohh.php
- whgohy.php
- shoheg.php
- xoghgh.php
- eoirhh.php
- dhbgbb.php
- gheowt.php
- chtgot.php
- rthghh.php
- fbhbbt.php
- vhgbgw.php
- thgowe.php
- wehowe.php
- yhhbwe.php
- ndsewt.php
- klgewo.php
As of this writing, the said sites are inaccessible.
SOLUTION
8.900
Step 1
For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.
Step 2
Identify and terminate files detected as BKDR_POSTBOT.ER
- If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
- If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.
Step 3
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.
- In HKEY_LOCAL_MACHINE
- tmp123
- tmp123
Step 4
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
- MMID = {hex values}
- MMID = {hex values}
Step 5
Search and delete these files
Step 6
Scan your computer with your Trend Micro product to delete files detected as BKDR_POSTBOT.ER. 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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