Trojan-Dropper.Win32.Checkin

Parent class: TrojWare

Trojans are malicious programs that perform actions which are not authorized by the user: they delete, block, modify or copy data, and they disrupt the performance of computers or computer networks. Unlike viruses and worms, the threats that fall into this category are unable to make copies of themselves or self-replicate. Trojans are classified according to the type of action they perform on an infected computer.

Class: Trojan-Dropper

Trojan-Dropper programs are designed to secretly install malicious programs built into their code to victim computers. This type of malicious program usually save a range of files to the victim’s drive (usually to the Windows directory, the Windows system directory, temporary directory etc.), and launches them without any notification (or with fake notification of an archive error, an outdated operating system version, etc.). Such programs are used by hackers to: secretly install Trojan programs and/or viruses protect known malicious programs from being detected by antivirus solutions; not all antivirus programs are capable of scanning all the components inside this type of Trojans.

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Platform: Win32

Win32 is an API on Windows NT-based operating systems (Windows XP, Windows 7, etc.) that supports execution of 32-bit applications. One of the most widespread programming platforms in the world.

Description

Technical Details

Checkin is a "downloader" trojan that downloads a given file from a certain site and runs it. The trojan itself is a Windows PE EXE file, written in MS Visual C++.

The trojan file sizes are of the following approximate sizes:
"Checkin.a": 50Kb
"Checkin.b": 45Kb

The trojan EXE file does not copy itself to any directory but creates a system registry auto-run key:

 "Checkin.a": 

 HKCUSoftwareMicrosoftWindowsCurrentVersionRun
  SysReg = %SystemDir%SysReg

 "Checkin.b": 

 HKCUSoftwareMicrosoftWindowsCurrentVersionRun
  OWMngr = %SystemDir%OWMngr.exe

It seems that the trojan program should be completed by an "installator" that performs all steps for installing the trojan program into the system.

The trojan program also creates more registry keys:

 HKCUSoftwareIExplore   Ads
   AID
   ID
   LoggedIn

It uses these keys for its 'internal' needs.

Checkin then becomes an active process (this process is visible in the task list), downloads a file from a Web site, stores it on the hard disk using the name update.exe and executes this file.

The Web site name and remote file URL can vary. The Checkin trojan downloads this information from another Web site:

 
 "Checkin.a":  http://tp.searchseekfind.com
 "Checkin.b":  http://ads.onwebmedia.com
  

At these locations the trojan uses the "Checkin.pl" file.

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