Virus:Worm/Locksky.AA
Date discovered:16/01/2006
Type:Worm
In the wild:Yes
Reported Infections:Low
Distribution Potential:Medium
Damage Potential:Medium
Static file:Yes
File size:29.053 Bytes
MD5 checksum:698cce51538c54460844b8388f1f0B1d
VDF version:6.33.0.125

 General Method of propagation:
   • Email


Aliases:
   •  Symantec: W32.Looksky.G@mm
   •  Kaspersky: Email-Worm.Win32.Locksky.ab
   •  TrendMicro: WORM_LOCKSKY.AM
   •  F-Secure: Email-Worm.Win32.Locksky.ab
   •  Sophos: W32/Locksky-AB
   •  Panda: W32/Locksky.AU.worm
   •  VirusBuster: I-Worm.Locksky.AP
   •  Eset: Win32/Locksky.AH
   •  Bitdefender: Win32.Locksky.AN@mm


Platforms / OS:
   • Windows 95
   • Windows 98
   • Windows 98 SE
   • Windows NT
   • Windows ME
   • Windows 2000
   • Windows XP
   • Windows 2003


Side effects:
   • Drops malicious files
   • Records keystrokes
   • Registry modification
   • Steals information
   • Third party control

 Files It copies itself to the following locations:
   • %WINDIR%\sachostx.exe
   • %malware execution directory%\temp.bak



It deletes the following file:
   • %SYSDIR%\hard.lck



The following files are created:

– %SYSDIR%\msvcrl.dll Further investigation pointed out that this file is malware, too. Detected as: Worm/Locksky.P.9

– %SYSDIR%\sachostp.exe Furthermore it gets executed after it was fully created. Further investigation pointed out that this file is malware, too. Detected as: Worm/Locksky.V.1.B

– %SYSDIR%\sachostc.exe Furthermore it gets executed after it was fully created. Further investigation pointed out that this file is malware, too. Detected as: BDS/Locksky.K

– %SYSDIR%\sachostw.exe Furthermore it gets executed after it was fully created. Further investigation pointed out that this file is malware, too. Detected as: Worm/Locksky.T.6

– %SYSDIR%\sachosts.exe Furthermore it gets executed after it was fully created. Further investigation pointed out that this file is malware, too. Detected as: Worm/Locksky.V.1.C




It tries to download a file:

– The locations are the following:
   • http://proxy4u.ws:8080/**********
   • http://proxy4u.ws:8080/**********
   • http://usproxy2u.ws:8080/**********
   • http://usproxy2u.ws:8080/**********
At the time of writing this file was not online for further investigation.

 Registry The following registry key is added in order to run the process after reboot:

– HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
   • "HostSrv" = "%WINDIR%\sachostx.exe"



It creates the following entry in order to bypass the Windows XP firewall:

– HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\
   FirewallPolicy\StandardProfile\AuthorizedApplications\List
   • "%malware execution directory%\%executed file% "="%malware execution directory%\ %executed file% :*:Enabled:enable"
   • "%SYSDIR%\sachostw.exe"="%SYSDIR%\sachostw.exe:*:Enabled:enable"
   • "%SYSDIR%\sachostc.exe"="%SYSDIR%\sachostc.exe:*:Enabled:enable"
   • "%SYSDIR%\sachosts.exe"="%SYSDIR%\sachosts.exe:*:Enabled:enable"

 Email It contains an integrated SMTP engine in order to send emails. A direct connection with the destination server will be established. The characteristics are described in the following:


From:
The sender address is spoofed.


To:
– Email addresses found in specific files on the system.
– Email addresses gathered from WAB (Windows Address Book)


Subject:
The following:
   • Your mail Account is Suspended



Body:
The body of the email is the following:

   • We regret to inform you that your account has been suspended due to the violation of our site policy, more info is attached.


Attachment:
The filename of the attachment is one of the following:
   • acc_info9.exe
   • ebay_info.exe
   • acc_inf19.exe

The attachment is a copy of the malware itself.

 Mailing Search addresses:
It searches the following file for email addresses:
   • htm

 Backdoor The following ports are opened:

– %SYSDIR%\sachosts.exe on a random TCP port in order to provide an HTTP server.
– %SYSDIR%\sachostc.exe on a random TCP port in order to provide a proxy server.


Contact server:
The following:
   • http://proxy4u.ws/index.php?

As a result it may send some information.

Sends information about:
    • IP address
    • Current malware status
    • Opened port

 Injection –  It injects the following file into a process: %SYSDIR%\msvcrl.dll

    Process name:
   • %all running processes%


 File details Runtime packer:
In order to aggravate detection and reduce size of the file it is packed with the following runtime packer:
   • UPX

Description inserted by Irina Boldea on Tuesday, April 18, 2006
Description updated by Irina Boldea on Thursday, April 20, 2006

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