F-Secure
Tools
Worm:W32/AutoRun.GM
Summary
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.
Details
File System Changes
Creates these files:
- %Programfiles%\Microsoft Common\wuauclt.exe
Network Connections
Attempts to download files from:
- http://aaszxt.ru/load4/[...].php?v=1&rs=%VolumeSerialNumber%&n=1&uid=1
Registry Modifications
Sets these values:
- HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\explorer.exe
Debugger = "%Programfiles%\Microsoft Common\wuauclt.exe"
- HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
svchost = "%Programfiles%\Microsoft Common\wuauclt.exe"
Additional Details
Execution
Upon execution, the malware first creates a copy of itself in the program files, then amends the registry to ensure automatic execution.
It also creates the following files in all removable drives found in the system:
The system.exe file is a copy of itself, while the autorun.inf contains the following strings:
Downloads
The malware attempts to download files from:
Note: %VolumeSerialNumber% is volume serial number that the operating system assigns when a hard disk is formatted.
Stealth
For its stealth routine, it injects malicious code into the one of the following normal process:
Note: %program% is usually "C:\Program Files\Internet Explorer\IEXPLORE.EXE -nohome" which was taken under the registry key "HKEY_CLASSES_ROOT\http\shell\open\command, (Default)".
It also removes the hooked addresses corresponding to various NT Functions implemented in Ntoskrnl.exe, then restores them to their original values.
The malware will attempt to make the changes by exploiting the GDI Local Elevation of Privilege Vulnerability (CVE-2006-5758), which in unpatched machines allows a remote attacker to gain direct access to the kernel. If this method fails, it drops and executes a special driver that restores the pointers:
The malware creates and executes a kernel service driver as either of the following:
Both these files are detected as Rootkit:W32/Agent.UG.
It will query all services under the following registry entries, to obtain the %service_path_and_filename% and %servicename% of services that have:
It also creates the following registry entries to bypass the Windows Firewall:
Additionally, it creates a window with Classnames= "WNDCLASSXEMORES".
Upon execution, the malware first creates a copy of itself in the program files, then amends the registry to ensure automatic execution.
It also creates the following files in all removable drives found in the system:
- system.exe
- autorun.inf
The system.exe file is a copy of itself, while the autorun.inf contains the following strings:
- [autorun]
open=system.exe
shellexecute=system.exe
shell\Explore\command=system.exe
shell\Open\command=system.exe
shell=Explore
Downloads
The malware attempts to download files from:
- http://aaszxt.ru/load4/[...].php?v=1&rs=%VolumeSerialNumber%&n=1&uid=1
Note: %VolumeSerialNumber% is volume serial number that the operating system assigns when a hard disk is formatted.
Stealth
For its stealth routine, it injects malicious code into the one of the following normal process:
- svchost.exe
- %program%
Note: %program% is usually "C:\Program Files\Internet Explorer\IEXPLORE.EXE -nohome" which was taken under the registry key "HKEY_CLASSES_ROOT\http\shell\open\command, (Default)".
It also removes the hooked addresses corresponding to various NT Functions implemented in Ntoskrnl.exe, then restores them to their original values.
The malware will attempt to make the changes by exploiting the GDI Local Elevation of Privilege Vulnerability (CVE-2006-5758), which in unpatched machines allows a remote attacker to gain direct access to the kernel. If this method fails, it drops and executes a special driver that restores the pointers:
- NtProtectVirtualMemory
- NtOpenThread
- NtTerminateThread
- NtCreatePort
- NtConnectPort
- NtCreateKey
- NtAdjustPrivilegesToken
- NtCreateFile
- NtWriteVirtualMemory
- NtOpenProcess
- NtCreateProcess
- NtCreateProcessEx
- NtCreateSection
- NtCreateThread
- NtDeleteKey
- NtDeleteValueKey
- NtDuplicateObject
- NtEnumerateKey
- NtEnumerateValueKey
- NtLoadDriver
- NtLoadKey
- NtLoadKey2
- NtNotifyChangeKey
- NtOpenFile
- NtOpenKey
- NtOpenSection
- NtQueryKey
- NtQueryMultipleValueKey
- NtQueryValueKey
- NtReplaceKey
- NtRestoreKey
- NtResumeThread
- NtSaveKey
- NtSetContextThread
- NtSetInformationFile
- NtSetInformationKey
- NtSetSystemInformation
- NtSetValueKey
- NtSuspendThread
- NtSystemDebugControl
- NtTerminateProcess
The malware creates and executes a kernel service driver as either of the following:
- %systemdir%\Drivers\%servicename%.sys
- %service_path_and_filename%
Both these files are detected as Rootkit:W32/Agent.UG.
It will query all services under the following registry entries, to obtain the %service_path_and_filename% and %servicename% of services that have:
- Service Type = SERVICE_KERNEL_DRIVER and Start= SERVICE_DEMAND_START:
- HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\%servicename%
It also creates the following registry entries to bypass the Windows Firewall:
- HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters
\FirewallPolicy\StandardProfile\AuthorizedApplications\List
{malware_executed_path_and_filename} = "{malware_executed_path_and_filename}:*:Enabled:EMOTIONS_EXECUTABLE"
Additionally, it creates a window with Classnames= "WNDCLASSXEMORES".