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Aliases: Trojan:Java/Spoilder.A (Microsoft), Trojan.Maljava (Symantec), Generic.dx!bfdx (McAfee), Trojan-Dropper.Java.Agent.n (Kaspersky)
Malware type: Trojan
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003, Mac OS X
Encrypted: No
In the wild: Yes


Infection Channel: Downloaded from the Internet

This Trojan executes when a user accesses certain websites where it is hosted.

Technical Details

File size: 3,853 bytes
File type: Java Class
Initial samples received date: 26 Jul 2012
Payload: Drops files

Arrival Details

This Trojan executes when a user accesses certain websites where it is hosted.


It determines the operating system where it is executing.

If the operating system is Windows, it drops and executes the following file:

  • %User Temp%\~spawn{random number}.tmp.dir\payload.exe - detected by Trend Micro as WORM_MORCUT.A
If the malware is running in Mac OS X, it drops and executes the following file:
  • $TMPDIR/~spawn{random number}.tmp.dir/payload.exe - detected by Trend Micro as OSX_MORCUT.A

Where $TMPDIR is usually /var/folders/cr/{random characters}/T.


Minimum scan engine: 9.200
First VSAPI Pattern File: 9.286.02
First VSAPI Pattern Release Date: 26 Jul 2012
VSAPI OPR Pattern Version: 9.287.00
VSAPI OPR Pattern Release Date: 27 Jul 2012

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

Remove malware/grayware files dropped/downloaded by JAVA_MORCUT.A

Step 3

Close all opened browser windows

Step 4

Scan your computer with your Trend Micro product to delete files detected as JAVA_MORCUT.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 this Knowledge Base page for more information.

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Analysis By: Christopher Daniel So

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