BKDR_ZACCESS.M
Microsoft : TrojanDropper:Win32/Sirefef.B; Kaspersky : Backdoor.Win32.ZAccess.et
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This backdoor may be unknowingly downloaded by a user while visiting malicious websites.
It connects to a website to send and receive information.
It also has rootkit capabilities, which enables it to hide its processes and files from the user.
TECHNICAL DETAILS
232,798 bytes
EXE
Yes
28 Jul 2011
Arrival Details
This backdoor may be unknowingly downloaded by a user while visiting malicious websites.
Installation
This backdoor injects codes into the following process(es):
- explorer.exe
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CLASSES_ROOT\Interface\{SID}
Backdoor Routine
This backdoor connects to the following websites to send and receive information:
- {BLOCKED}212.157
- {BLOCKED}er.yadro.ru
Rootkit Capabilities
This backdoor also has rootkit capabilities, which enables it to hide its processes and files from the user.
NOTES:
It creates the following folder where it stores its components such as configuration files, component malware, plugins, and possibly malicious downloaded file(s):
- %WINDOWS%\$NtUninstallKB{numbers}$
(%Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
It employs a DGA routine based on the current date in order to generate an ".cn" as its comain name extension. It uses the generated domain for phoning home via HTTP GET request with the following format:
- http://{8 random characters).cn/stat2.php?w={parameter}&i={parameter}&a={parameter}
- http://{8 random characters).cn/bad.php?w={parameter}&fail={parameter}&i={parameter}
As of writing, the generated domain points to the IP address {BLOCKED}9.{BLOCKED}0.212.157, which is currently inaccessible.
It is capable of terminating security software and forensic tools that it finds accessing its components. It may also reset the access control list (ACL) setting of the terminated process's file, thus, effectively preventing it from executing again.
It is capable of overwriting a legitimate driver in the system as part of its installation and to execute itself during system startup.
SOLUTION
8.900
8.326.06
28 Jul 2011
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
Since this malware uses rootkit technology, detection and removal using normal and safe mode methods may not eliminate it completely. This procedure restarts the system using the Windows Recovery Console.
- Insert the Windows Installation CD into the CD drive, then Press the restart button.
- Upon prompt, press any key to boot from the CD.
- On the main menu, type r to go to the Recovery Console.
- Type the drive that contains Windows (usually C:) and press Enter.
- In the input box, type the following then press Enter:
rd /s /q %WINDOWS%\$NtUninstallKB{numbers}$ - Type exit and press Enter to restart the system normally.
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_CLASSES_ROOT\Interface
- {SID}
- {SID}
Step 4
Scan your computer with your Trend Micro product to delete files detected as BKDR_ZACCESS.M. 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.