Aler is a network worm that was widely mass-mailed with the subject "Latest News about Arafat!!!". The attachments contain a regular JPEG and and custom-crafted EMF file which exploits the EMF (MS04-032) vulnerability. The worm does not use the exploit for propagation. Aler propagates to hosts with weak user passwords.
The clean image looked like this:
The payload of the worm is a multi component TCP proxy trojan.
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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:
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.