F-Secure Virus Descriptions : Aler
[Summary] | [Detailed Description] | [Detection]
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| NAME: | Aler |
| ALIAS: | Worm.Win32.Aler.a, Backdoor.Win32.Small.bq |
| ALIAS: | Golten, W32/Golten.worm, Exploit.Win32.MS04-032.a |
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.
System Infection
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).
Network Propagation
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
ADMIN$\System32\Alerter.exe
ADMIN$\System32\Alerter16.exe
then starts them as a service.
Payload
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.
Detection for this malware was published on November 11th, 2004
in the following F-Secure Anti-Virus updates:
[FSAV_Database_Version]
Version=2004-11-11_02
Detection for the MS04-032 exploit was added on October 22nd, 2004
in update version
FSAV_Database_Version]
Version=2004-10-22_01
Technical Details:
Gergely Erdelyi, November 16th, 2004;
F-Secure Corporation
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