hello list, This is actually a DESIGN BUG OF MOST(ALL?) Antivirus & trojan scanners. ( ROOTKIT SCANNERS already DO THIS ) This issue is a MORE THAN 1 YEAR OLD stuff but i see no fix till now!!!! lately i've ONLY tested it on the following AV & few other spyware scanner & saw its still NOT fixed! Kaspersky Anti-Virus 6.x (latest) BitDefender 9 Professional Plus (latest) NOD32 (latest) OS tested: WINxp sp2 to keep things simple, let me give you a situation; if there is a directory/file a EVIL_USER is willing to hide from antivirus scanner all he has to do is fire up a command prompt & run the command; cacls.exe TORJANED_FILE_OR_DIRECTORY_NAME /T /C /P EVIL_USER:R next time EVEN when the administrator starts the antivirus "system scan" the TORJANED_FILE_OR_DIRECTORY_NAME will be effectively bypassed as the ownership of the directory is just of the user account named; EVIL_USER and the antivirus "manual scan" is running just with the privilage of ADMINISTRATOR by this way a malicious executable can remain hidden in the system BYPASSING THE SCAN even when the AV scanner is run by administrator!!! BUT there isn't a compulsion that there should be a user with a malicious intension to get this condition & bypass the scan. there is another DUMB equivalent of the above cacls.exe command; Right click a folder, Properties > Sharing Tab >> Check on the tick mark of >> Make this Folder Private by doing so a user might me thinking he is making a folder not_accessable_to_any_other_system_user BUT by doing so... the directory gets effectively sciped by a AV scannner vulnerable to this trick. SOLUTION: AV already running with administrative privilage if the system administrator is starting manual scan, so what does AV should do is excelate its (manual scan) OF THE ANTIVIRUS SCANNER ENGINE/DRIVER (not the GUI) privilage to SYSTEM before starting the scan which will effectively bypass file permission & be able to scan the locked file with any file permission in Windows! And one more thing, if during AV scan if a file can't be opened due to some processes LOCKING the file.... Instead of going through the regular file open process AV should instead directly read the SECTORS of the hdd holding the locked file and examine if there is sething malicious (which still some AV don't do & instead just report the file(s) as locked!) am i clear??? Discussions, welcome! --- Bipin Gautam http://bipin.tk Zeroth law of security: The possibility of poking a system from lower privilege is zero unless & until there is possibility of direct, indirect or consequential communication between the two...
