Infection vectors; - ----------------- a) Email as an attachment of MIME audio/x-wav type. b) By browsing an infected webserver with Javascript execution enabled and using a version of IE vulnerable to the exploits discussed in MS01-020 (e.g. IE 5.0 or IE 5.01 without SP2). c) Machine to machine in the form of IIS attacks (primarily attempting to exploit vulnerabilities created by the effects of Code Red II, but also vulnerabilities previously patched by MS00-078) d) Highlighting either a .eml or .nws in Explorer with Active Desktop enabled (W2K/ME/W98 by default) then the THUMBVW.DLL will execute the file and attempt to download the README.EXE referenced in it (depending on your IE version and zone settings). e) Mapped drives. Any infected machine which has mapped network drives will likely infect all of the files on the mapped drive and its subdirectories To prevent yourself from being infected; a) Ensure all IE versions have applied MS01-027 (or are IE 5.01SP2 or above) b) Disable Active Scripting in IE c) Ensure all IIS installations have applied MS01-044 (or at the very least MS01-033) d) Use the CALCS program to modify the permissions on TFTP.EXE to remove all use; CALCS %systemroot%/system32/tftp.exe /D Everyone CALCS %systemroot%/system32/tftp.exe /D System Do the same for CMD.EXE (note, this could be tried with THUMBVM.DLL as well, haven't tried this myself yet) e) Ensure that TFTP is not permitted out through your network gateway (note that newly infected machines may try and TFTP *internally* from some other infected machine you have on your network) f) Modify or remove; HKEY_CLASSES_ROOT.eml HKEY_CLASSES_ROOT.nws Cleansing information; - --------------------- Nimda is viral, so while you can remove various files that it drops it probably will not be cleaned completely by manual means. This means you will have to use your AntiVirus vendor's product to completely cleans. a) Load.exe dropped as hidden/system file (probably in %systemroot%) b) Riched20.dll dropped with today's date as hidden/system file. c) Readme.exe dropped in every directory d) Admin.dll dropped in /scripts and/or root directories (not the _vti_bin directories of FrontPage) e) .eml and .nws files dropped in every directory f) Possibly modified your default home page in web dirs. g) Infected numerous files (if not all files) with the 56kb executable. h) Reports of people having files lumped together into .eml files Check with your AV Vendor regularly for updates to the cleansing programs. I would appreciate any reports from AV Vendors as to how complete they feel their cleaners currently are. I will do an update later tonight based on responses. Cheers, Russ - Surgeon General of TruSecure Corporation/NTBugtraq Editor
Hızla yayıldığı belirtilen bu ' worm ' hem e-mail attachment ile ( readme.exe ) hem de Microsft IIS
serverda 15 Mayıs 2001'de bulunan bir güvenlik açığını ( PWS Escaped Characters Decoding Command
Execution Vulnerability ) kullanarak yayılabilmektedir.
Ayrıca, Internet Explorer 5.0 veya 5.5 kullanılarak web ( http ) üzerinden mailboxlara ( hotmail, yahoo, vs..) erişim
söz konusu olduğunda, yine bir başka güvenlik açığını kullanarak bu mesaj okunduğunda ve hatta sadece
önizleme penceresinde görüntülendiğinde dahi sisteme bulaşabilmektedir.
Sundance`den not: Oldukça zararlı bir virus/worm olduğundan dolayı bu haberi biran önce çözümüyle birlikte girmek istedim. Şu an için çözümü türkçeye çevirebilecek zamanım yok, en kısa zamanda Türkçesini de yayınlayacağız.
