This app is viable if for no other reason than it works on OS X 10.5. Apple has stopped supporting OS versions before Snow Leopard so there's no Java update for Leopard users. They might appreciate a tool that can check their systems for infection. Indeed, so might Tiger users. That said, they would all be well advised in the now riskier climate for Mac security to install an app like ClamXav that still supports older Macs.

I have serious doubts about the credibility of the people claiming this trojan infected 600,000 Mac computers. I think the numbers are a outright lie and exaggerated to scare people into buying AV software. I was not infected, none of my friends or family were infected. And none of the 10,000+ worldwide clients the company I work for had a single reported infection.

You may also try the Kaspersky Flashfake Trojan removal tool :

info:
http://www.securelist.com/en/blog/208193454/Flashfake_Removal_Tool_and_online_checking_site

Download:
http://support.kaspersky.com/downloads/utils/flashfake_removal_tool.zip

:)

Be cautious of relying on scripts like this one. It is based on instructions for a specific variant from F-Secure, which do not work for all variants. It would be better to rely on some good anti-virus software, like Sophos Anti-Virus for Mac Home Edition or ClamXav, both of which are completely free, with no subscriptions or time limitations. And no, I'm not associated with either product.

This may not be the most sophisticated software, but the developer has responded quickly and provided it for free (so far there's nothing else on MacUpdate - their review process is somewhat quirky.)

I checked the script and it's not a trojan installer as one user suggested.

See for yourself:

--
-- Anti Flashback-Trojan
--
-- Created by Moritz Wette on 06.04.12.
-- Copyright 2012 Moritz Wette. All rights reserved.
--

on scan1()
try
set command to do shell script "defaults read /Applications/Safari.app/Contents/Info LSEnvironment"
--set output to words of (do shell script command)
return true
on error errmsg
if (errmsg contains "does not exist") then return false
end try
end scan1
on scan2()
try
do shell script "defaults read ~/.MacOSX/environment DYLD_INSERT_LIBRARIES "
return true
on error errmsg
if (errmsg contains "does not exist") then return false
end try
end scan2
on scan3()
try
do shell script "defaults read /Applications/Firefox.app/Contents/Info LSEnvironment"
return true
on error errmsg
if (errmsg contains "does not exist") then return false
end try
end scan3
on scan4()
try
do shell script "defaults read /Applications/Google Chrome.app/Contents/Info LSEnvironment"
return true
on error errmsg
if (errmsg contains "does not exist") then return false
end try
end scan4

(*on remove1()
try
do shell script "grep -a -o '__ldpath__[ -~]*' " + scan1_return
on error errmsg
display dialog errmsg
end try
try
do shell script "sudo defaults delete /Applications/Safari.app/Contents/Info LSEnvironment"
on error errmsg
display dialog errmsg
end try
try
do shell script "sudo chmod 644 /Applications/Safari.app/Contents/Info.plist"
on error errmsg
display dialog errmsg
end try
end remove1*)
(*on remove2()
try
do shell script "grep -a -o '__ldpath__[ -~]*' %path_obtained_in_step9%"
on error errmsg
display dialog errmsg
end try
try
do shell script "defaults delete ~/.MacOSX/environment DYLD_INSERT_LIBRARIES"
on error errmsg
display dialog errmsg
end try
try
do shell script "launchctl unsetenv DYLD_INSERT_LIBRARIES"
on error errmsg
display dialog errmsg
end try
end remove2*)

on run
set f to 0
scan1()
if (scan1() = true) then set f to f + 1
scan2()
if (scan2() = true) then set f to f + 1
scan3()
if (scan1() = true) then set f to f + 1
scan4()
if (scan2() = true) then set f to f + 1

if (f > 0) then
set temp to display dialog "Your computer is infected!" with icon 0 buttons {"Okay"}
if (button returned of result = "Remove The Flashback-Trojan") then
--if (scan1() = true) then remove1()
--if (scan2() = true) then remove2()
--display dialog "Your computer should be clean now!"
--open location "http://www.moritzwette.com/donate"
end if
else
display dialog "Your computer may be clean!"
open location "http://www.moritzwette.com/donate"
end if

end run

Downloaded the new version. Tried to open it, but it gave me twice an error message ...