TROJ_ZLOB.BYB
TrojanDownloader:Win32/Zlob.gen!T, TrojanDownloader:Win32/Zlob.gen!O (Microsoft); Puper (McAfee); Trojan.Zlob.N (Symantec); Trojan-Downloader.Win32.Zlob.cys (Kaspersky); Trojan-Downloader.Win32.Zlob.a (v) (Sunbelt); Downloader.Zlob (AVG)
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
TECHNICAL DETAILS
27,136 bytes
EXE
No
25 May 2013
Arrival Details
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Autostart Technique
This Trojan registers itself as a BHO to ensure its automatic execution every time Internet Explorer is used by adding the following registry keys:
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{D579A683-0CC7-4023-BAE7-0544D0D1DA3A}
Other System Modifications
This Trojan adds the following registry keys:
HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{D579A683-0CC7-4023-BAE7-0544D0D1DA3A}
HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{D579A683-0CC7-4023-BAE7-0544D0D1DA3A}\InprocServer32
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
explorer\run
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Search
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{D579A683-0CC7-4023-BAE7-0544D0D1DA3A}
xxx = "xxx"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{D579A683-0CC7-4023-BAE7-0544D0D1DA3A}\InprocServer32
ThreadingModel = "Apartment"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
explorer\run
start = "{malware path and file name}"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Start Page = "about:blank"
(Note: The default value data of the said registry entry is http://www.microsoft.com/isapi/redir.dll?prd=ie&pver=6&ar=msnhome.)
Dropping Routine
This Trojan drops the following files:
- %System Root%\isfmdl.dll
- %System Root%\isfmm.exe
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
This report is generated via an automated analysis system.
SOLUTION
9.300
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
Close all opened browser windows
Step 3
Delete this registry key
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_LOCAL_MACHINE\Software\Classes\CLSID
- {D579A683-0CC7-4023-BAE7-0544D0D1DA3A}
- In HKEY_LOCAL_MACHINE\Software\Classes\CLSID\{D579A683-0CC7-4023-BAE7-0544D0D1DA3A}
- InprocServer32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\explorer
- run
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
- Search
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_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{D579A683-0CC7-4023-BAE7-0544D0D1DA3A}
- xxx = "xxx"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{D579A683-0CC7-4023-BAE7-0544D0D1DA3A}\InprocServer32
- ThreadingModel = "Apartment"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\explorer\run
- start = "{malware path and file name}"
Step 5
Restore these modified registry values
Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- From: Start Page = "about:blank"
To: Start Page = ""http://www.microsoft.com/isapi/redir.dll?prd=ie&pver=6&ar=msnhome""
- From: Start Page = "about:blank"
Step 6
Search and delete these components
- %System Root%\isfmdl.dll
- %System Root%\isfmm.exe
Step 7
Scan your computer with your Trend Micro product to delete files detected as TROJ_ZLOB.BYB. 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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