A standalone malicious program which uses computer or network resources to make complete copies of itself. May include code or other malware to damage both the system and the network.
S60 phones have a list of valid certificates. To maintain a current list of valid certificates, the application manager settings should be adjusted from the defaults. The default App. manager setting for Online certif. check is Off.
The On setting is necessary to remove revoked certificates from your phone during installation.
Online Certificate Check details from Nokia:
- You should have network access to install applications if check is on.
- This may pose cost of data transfer to you.
- "On" means that if the connection to the server fails, installation can be done. A revocated application can in that case be installed.
- "Must be passed" means that if the connection to the server fails, you will not be able to install.
Yxe does not utilize a hidden interface. If the App manager is available, Yxe can be removed. The user only needs to locate the application name that was presented during installation. Example: Sexy View.
The log file (mr.log) and the SISX file (root.sisx) will not be deleted during uninstallation.
Worm:SymbOS/Yxe is the first malicious software to target Symbian S60 3rd Edition Phones.
Worm:SymbOS/Yxe variants are complied for S60 3rd Edition phones and will not install on older Symbian phones.
Variants of Worm:SymbOS/Yxe include:
Social engineering is used to entice the user into installing Yxe.
The installer prompts the user to install "Sexy View" by the vendor "Play Boy".
The user is offered English and Chinese language options. However, there is no user interface.
Yxe variants have been Symbian signed using a valid certificate. They will install normally on S60 3rd Edition phones. The certificate used by Yxe are in the process of being revoked. The disinfection section contains additional details regarding certificates.
Yxe starts automatically when the phone boots and attempts to terminate:
Yxe attempts to avoid debugging and terminates the processes of many third party file/process viewing utilities.
Yxe collects data about the phone.
It will attempt to open an HTTP connection in order to upload the data and keeps the connection open at all times.
The domain list to which Yxe attempts to connect is encrypted within the code of Yxe.
Once connected it starts writing a log file called mr.log. It creates a sis file named "c:\data\root.sisx".
Yxe modifies the file C:\system\data\System.ini.
It will attempt to send SMS messages to the phone's contact list.
Worm:SymbOS/Yxe will uninstall itself. The name in the application manager depends on the variant.
The name "Sexy View" has been used by early Yxe variants. See the disinfection section for additional details.