JAVA_CRAT.A
Backdoor.Java.CrossRAT.b (Kaspersky); Backdoor.Java.CrossRat (Ikarus); Java.Backdoor.Crossrat.Ebqt (Tencent)
Windows
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
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.
It runs certain commands that it receives remotely from a malicious user. Doing this puts the affected computer and information found on the computer at greater risk.
TECHNICAL DETAILS
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 depending on the platform/operating system of the affected computer:
- %User Temp%\mediamgrs.jar
(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
Autostart Technique
This Backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
mediamgrs = "%Program Files%\Java\{Java Version}\bin\javaw.exe -jar %User Temp%\mediamgrs.jar"
Backdoor Routine
This Backdoor executes the following command(s) from a remote malicious user:
- Enumerate root directories
- Enumerate files
- Create blank file
- Copy File
- Move file
- Write file contents
- Read file contents
- Heartbeat request
- Get screenshot
- Run a DLL
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- http://{BLOCKED}rry.com:2223/
SOLUTION
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
Identify and terminate files detected as JAVA_CRAT.A
- Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
- 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 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\Run
- mediamgrs = "%Program Files%\Java\{Java Version}\bin\javaw.exe -jar %User Temp%\mediamgrs.jar"
- mediamgrs = "%Program Files%\Java\{Java Version}\bin\javaw.exe -jar %User Temp%\mediamgrs.jar"
Step 5
Scan your computer with your Trend Micro product to delete files detected as JAVA_CRAT.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 the following Trend Micro Support pages for more information:
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