When the EMF attachment is opened the exploit triggers, which results in a chain-reaction of droppers. The following files are created in the Windows System directory:
- SP00LSV.EXE - main dropper that drops the rest of the files
- Alerter.exe - copy of the main dropper
- Alerter16.exe - copied there during network infection
- SPC.EXE - Backdoor dropper
- SCardSer.exe - Backdoor injector
- comsock.dll (renamed to comwsock.dll) - Backdoor injector
- sockup.dll (renamd to dmsock.dll) - Main backdoor component
- SPTRES.DLL - Network propagation routines
SPTRES.DLL is injected into EXPLORER.EXE, comsock.dll is injected into LSASS.EXE and dmsock.dll is injected into a number of other processes (eg. IEXPLORE.EXE, OUTLOOK.EXE, etc).
The network propagation routine of Aler is very simple. It scans random IP addresses for Windows computers. If it finds one, the worm attempts to connect to it using user credentials from the infected computer as well as a list of predefined passwords (eg. 1234, pass, etc). If the connection is successful the Aler copies the main dropper to the remote computer as
then starts them as a service.
The payload of Aler is a TCP proxy that allows the attacker to initiate network connections through the infected computer. This feature could be used to send SPAM, attack other computers, etc.
The backdoor components of Aler are detected as Backdoor.Win32.Small.bq.