Win32/Sober threat description - Microsoft Security Intelligence

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Published Feb 21, 2005 | Updated Sep 15, 2017

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Detected by Microsoft Defender Antivirus

Aliases: No associated aliases

Windows Defender Antivirus detects and removes this threat.

Win32/Sober is a family of mass-mailing worms that targets certain versions of Microsoft Windows.

The worm sends itself as an attachment to email addresses that it finds in files on the infected PC. The worm is activated when a user opens the attachment.

Use the following free Microsoft software to detect and remove this threat:

Microsoft Defender Antivirus for Windows 10 and Windows 8.1, or Microsoft Security Essentials for Windows 7 and Windows Vista
Microsoft Safety Scanner

You should also run a full scan. A full scan might find hidden malware.

Get more help

You can also visit our advanced troubleshooting page or search the Microsoft virus and malware community for more help.

If you’re using Windows XP, see our Windows XP end of support page.

Threat behavior

When a variant of Win32/Sober runs, it takes the following actions:

Creates one or more files at <system folder>\<random>.exe and runs them.

Creates a registry value with data: <full path>
in registry keys:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
This causes the worm to run automatically whenever Windows starts.

Retrieves e-mail addresses that it finds in files on the infected computer, avoiding addresses that contain certain strings.
Creates the file <system folder>\<random>, where it saves those e-mail addresses.

Sends itself as an attachment to the e-mail addresses. The e-mail has a subject line and message body that is in English or German. The e-mail attachment may have one of the following extensions:
.bat
.exe
.pif
.src
.zip