User Agent

Mozilla/5.0 (Windows; U; ; en-US) AppleWebKit/533.3 (KHTML, like Gecko) SecondLife/3.7.23.297296 (Second Life Release; default skin) Safari/533.3

This user agent belongs to SecondLife. Linden Labs developed this Application. This Application run on Win32 and it renders web contents with WebKit on Windows Desktop.

Application - SecondLife

SecondLife

Version3.7 @ 32 bit
DeveloperLinden Labs
ParentSecondLife
Platform windows (32 bit) by Microsoft Corporation
Device TypeDesktop

Act as 

Mobile No
Tablet No
Crawler No
Fake No
Anonymized No

Capabilities

Rendering EngineWebKit by Apple Inc (For Google Chrome, iOS (including both mobile Safari, WebViews within third-party apps, and web clips), Safari, Arora, Midori, OmniWeb, Shiira, iCab since version 4, Web, SRWare Iron, Rekonq, and in Maxthon 3.)
Pointingmouse
Javascript Yes
CSS Yes Version: 3
Cookies Yes
Tables Yes
Frames Yes
IFrames Yes
Background Sounds No
Java Applets Yes
VB Script No
Activex No