ThreatExpert Report: Trojan.Generic, Trojan Horse, Trojan-Downloader.Win32.Agent.crco, Generic..

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Submission Summary:

Submission details:

Submission received: 22 November 2009, 06:36:47
Processing time: 7 min 49 sec
Submitted sample:

File MD5: 0x3D4A3FEBE3BC340AB391820591EC9822
File SHA-1: 0x31E54CB39329E55981D152573E0E7BE030A123D9
Filesize: 601,028 bytes
Alias:

Trojan.Generic [PCTools]
Trojan Horse [Symantec]
Trojan-Downloader.Win32.Agent.crco [Kaspersky Lab]
Generic Downloader.x!bqv [McAfee]

Summary of the findings:

What's been found	Severity Level
Downloads/requests other files from Internet.
Creates a startup registry entry.
Contains characteristics of an identified security risk.

Technical Details:

Possible Security Risk

Attention! The following threat categories were identified:

Threat Category	Description
	A program that downloads files to the local computer that may represent security risk
	A malicious trojan horse or bot that may represent security risk for the compromised system and/or its network environment

File System Modifications

The following files were created in the system:

#	Filename(s)	File Size	File Hash	Alias
1	%ProgramFiles%\Yahoo Helper\uninst.exe	157,900 bytes	MD5: 0xC1A6BCC751D5A251EDB78FF062D1F374 SHA-1: 0x61BCE5A5432CF5A91AC5ACB5BECBB97DFD5AAAF9	Trojan.Generic [PCTools] Trojan Horse [Symantec] Trojan-Downloader.Win32.Agent.crco [Kaspersky Lab] Trojan-Dropper.Agent [Ikarus]
2	%ProgramFiles%\Yahoo Helper\yahooh.dat	130 bytes	MD5: 0xD736086A6E0D5FF93FD5903B3B6E2C46 SHA-1: 0xD409984DB9774B1295137D4C5A3F8A79749944A2	(not available)
3	%ProgramFiles%\Yahoo Helper\yahooh.exe	65,536 bytes	MD5: 0x20E83A1AB31FC377A692185A7EA6D292 SHA-1: 0x3A84597B9E76BB0685D651CEA1977AFFAF65CED7	(not available)
4	%ProgramFiles%\Yahoo Helper\yahoohhk.dll	57,344 bytes	MD5: 0x7D152EF4F1301EDBF851025C34DEEB3D SHA-1: 0xEBFBCF63BC00EFB7EB40878A0A5A38EACB8C5F02	(not available)
5	%ProgramFiles%\Yahoo Helper\yahoohup.exe	801,792 bytes	MD5: 0xDB449BB050CC76BA6D310D933DD29210 SHA-1: 0x9EB8ECAF242115A9934307830593EBE6149E6BF0	(not available)
6	[file and pathname of the sample #1]	601,028 bytes	MD5: 0x3D4A3FEBE3BC340AB391820591EC9822 SHA-1: 0x31E54CB39329E55981D152573E0E7BE030A123D9	Trojan.Generic [PCTools] Trojan Horse [Symantec] Trojan-Downloader.Win32.Agent.crco [Kaspersky Lab] Generic Downloader.x!bqv [McAfee]

Note:

%ProgramFiles% is a variable that refers to the Program Files folder. A typical path is C:\Program Files.

The following directory was created:

%ProgramFiles%\Yahoo Helper

Memory Modifications

There was a new process created in the system:

Process Name	Process Filename	Main Module Size
yahoohup.exe	%ProgramFiles%\Yahoo Helper\yahoohup.exe	827,392 bytes

Registry Modifications

The following Registry Keys were created:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Yahoo Helper
HKEY_CURRENT_USER\Software\Yahoo Helper

The newly created Registry Values are:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main]

Enable Browser Extensions = "yes"

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Yahoo Helper]

DisplayName = "Yahoo Helper"
UninstallString = "%ProgramFiles%\Yahoo Helper\uninst.exe"
DisplayIcon = "%ProgramFiles%\Yahoo Helper\uninst.exe"
DisplayVersion = "1.0"
URLInfoAbout = ""
Publisher = "Yahoo Helper"

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main]

Enable Browser Extensions = "yes"

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run]

Yahoo Helper = "%ProgramFiles%\yahoo helper\yahoohup.exe"

so that yahoohup.exe runs every time Windows starts

[HKEY_CURRENT_USER\Software\Yahoo Helper]

SfNTqW7TrGkHXGyK = "aJkIbEk3aERIac"
partner = "inforever4"
SfNTqW7TApF2Xc = "aJkIbEmiaEYIac"
SfNTqW7TApDyrk = "aJkIbEk3aERIac"
SfNTqW7TQn0HXni0 = "aJkIbEmiaEYIac"
uid = "5FC8D78341AE4D8BB3E3CE23A52BE282"
Qf3urnN0qOLyrnY = "cuzReOPhXwPyqdLnQfiKRviXgfyhqULoXfiIXGo"
cp7hrmDyrne = "aJkIbdViadVUaY"
Connect = "OK"
date = "22"

Other details

Analysis of the file resources indicate the following possible country of origin:

Republic of Korea

There was registered attempt to establish connection with the remote host. The connection details are:

Remote Host	Port Number
210.172.216.242	80

The data identified by the following URLs was then requested from the remote web server:

http://www.wesearch.co.kr/ncount/count.php?tp=1&pt=inforever4&ctm=D3-10-B0-8F-1D-6D
http://www.wesearch.co.kr/yahooh/program/inf/inforever4.htm
http://www.wesearch.co.kr/yahooh/program/fil/cpq/2009111801/yahooh.exe
http://www.wesearch.co.kr/yahooh/program/fil/cpq/2009111801/yahoohhk.dll

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