Adware:W32/Apropos is a program that collects data on the user's browsing behavior in order to display targeted advertising content during each Web browsing session.
The program also uses a rootkit and highly sophisticated stealth techniques to avoid detection.
Please note that Apropos is not associated with Apropos Technologies, Inc (NASDAQ: APRS). The Apropas spyware family is produced by PeopleOnPage.
Apropos silently itself into a randomly named directory under the Program Files folder. Each installation is assigned a unique ID.
It also installs:
- One randomly named EXE file to the System32 folder
- One randomly named SYS file to the \System32\Drivers folder
In addition to the randomly named files, Apropos uses several statically named files that reside in the installation directory, such as ace.dll, data.bin and WinGenerics.dll. These files can be seen below (images from a log file):
Once installed, Apropos's rootkit implements a kernel-mode driver. The rootkit starts automatically early in the boot process and modifies important data structures and several native API functions in order to hide files, directories, registry keys and processes related to the adware.
Specifically, the following functions are patched:
Once the files and registry keys have been hidden, no user-mode process is allowed to access them.
Apropos collects information about the computer system and tracks the user's browsing habits. The collected information is forwarded to remote servers, together with the unique ID.
These servers run the ContextPlus engine, which is used by the public software POP! (also made by PeopleOnPage). When the client connects to the server, the name Apropos is used as the client name.
The ContextPlus engine tracks the following information related to the unique ID:
- Softwares installed on the machine
- User's browsing behavior
- Web sites visited
The information is used to return targeted advertising content whenever the application contacts the remote server.