Trojan:Win32/Simda is a multi-component trojan that downloads and executes arbitrary files. These files may include additional malware.
Installation
When executed, the malware:
- Checks if the trojan is running from the <system folder>. If it isn't running from the system folder, Trojan:Win32/Simda copies itself as <system folder>\<random_number>.exe
- Modifies the following registry entry to execute its copy at Windows start
Adds value: "userinit"
With data: "<system folder>\userinit.exe,<system folder>\<random_number>.exe,"
To subkey: HKLM\Software\Microsoft\Windows NT\Currentversion\Winlogon
- Injects code to the process “svchost.exe”
- Deletes the original executable
Note - <system folder> refers to a variable location that is determined by the malware by querying the Operating System. The default installation location for the System folder for Windows 2000 and NT is C:\Winnt\System32; and for XP, Vista, and 7 is C:\Windows\System32.
Payload
Downloads and executes arbitrary files
Trojan:Win32/Simda connects to a remote host and provides information regarding the newly infected computer.
It then receives the configuration information on where to download additional files, and other locations from which to download additional configuration files. Downloaded files are written to the %TEMP% folder, for example C:\Users\<user name>\AppData\Local\Temp. These files may include additional malware.
In the wild, we've observed the following domains being contacted for this purpose:
gusssiss.com
orlikssss.com
asterixsss.com
Modifies security settings
Trojan:Win32/Simda uses various techniques in an attempt to elevate its privilege. It attempts to log on as Administrator (if the user isn't Admin already) using a list of passwords:
-
help
-
stone
-
server
-
pass
-
idontknow
-
administrator
-
admin
-
666666
-
111
-
12345678
-
1234
-
soccer
-
abc123
-
password1
-
football1
-
fuckyou
-
monkey
-
iloveyou1
-
superman1
-
slipknot1
-
jordan23
-
princess1
-
liverpool1
-
monkey1
-
baseball1
-
123abc
-
qwerty1
-
blink182
-
myspace1
-
pop
-
user111
-
098765
-
qweryuiopas
-
qwe
-
qwer
-
qwert
-
qwerty
-
asdfg
-
chort
-
nah
-
xak
-
xakep
-
111111
-
12345
-
2013
-
2007
-
2207
-
110
-
5554
-
775
-
354
-
1982
-
123
-
password
-
123456
Injects code
If successful at privilege escalation, Simda attempts to inject a DLL into the process space of winlogon.exe. This DLL is detected as PWS:Win32/Simda.
Exploits vulnerabilities
Trojan:Win32/Simda also attempts to exploit the following vulnerabilities in order to assist in gaining elevated privileges:
Additional information
The retrieved domains are then saved to the following registry entries in an encrypted form, for example:
Adds value: “m1131”
With data: <encrypted URL>
To subkey: HKLM\Software\Microsoft
Adds value: “m1132”
With data: <encrypted URL>
To subkey: HKLM\Software\Microsoft
Adds value: “m1133”
With data: <encrypted URL>
To subkey: HKLM\Software\Microsoft
Analysis by Rodel Finones
