A Windows virus cannot affect OS X, but it can be passed on:
There are many forms of ‘Malware’ that can affect a computer system, of which ‘a virus’ is but one type, ‘trojans’ another. Using the strict definition of a computer virus, no viruses that can attack OS X have so far been detected 'in the wild', i.e. in anything other than laboratory conditions. The same is not true of other forms of malware, such as Trojans. Whilst it is a fairly safe bet that your Mac has NOT been infected by a virus, it may have another security-related problem, but more likely a technical problem unrelated to any malware threat.
You may find this User Tip on Viruses, Trojan Detection and Removal, as well as general Internet Security and Privacy, useful:
The User Tip (which you are welcome to print out and retain for future reference) seeks to offer guidance on the main security threats and how to avoid them.
More useful information can also be found here:
I recently received an email with a virus from a pc user. Emails were sent to everyone in her address book. I didnt open the file but did preview it. How can I find out if the (or any) virus is sitting on my computer, ready to infect my pc user friends (trojan horse?)
I'll just note that Klaus1 is exactly right about Windows viruses not impacting a Mac.
I tried downloading Avast, Clam etc. but none of them work on older OSX versions 10.4.11.
ClamXav v2.2.1 works with Tiger.
...Any help for us dinosaurs will be gratefully accepted,.
I'm sure I don't need to tell you that your OS was released five years ago and has not had an update in over three years. Use of Java in your browser makes you vulnerable to at least one drive-by Trojan and there could be more in the future. All but one recent malware attacks will only run on Intel Macs, but Tiger has none of the protective features of currently supported versions, making you vulnerable to many older bits of malware, though it's not likely many of them are in circulation.
What an invaluable reply! I am aware that I dont have to worry about pc viruses on my mac, but i did understand, as you said, that a trojan could be on my computer that i could inadvertently send to others. I have installed the clam software and am now scanning my hard drive. So far no problems have been found, Thank you again for your help, I've learned enough from your info to know just how much I really don't know!
I have installed the clam software and am now scanning my hard drive. So far no problems have been found
Just a word of caution, as many users new to ClamXav run into problems with their e-mail. Here's my standard guidance in case you find any allegedly infected e-mail:
Never use ClamXav (or any other A-V software) to move (quarantine) or delete e-mail. It will corrupt the mailbox index which could cause loss of other e-mail and other issues with functions such as searching. It may also leave the original e-mail on your ISP's e-mail server and will be re-downloaded to your hard drive the next time you check for new mail.
So, if you choose to "Scan e-mail content for malware and phishing" in the General Preferences, make sure you do not elect to either Quarantine or Delete infected files.
When possibly infected e-mail files are found:
- Right-click/Control-click on either the infection or file name in the ClamXav window.
- Select "Reveal In Finder" from the pop-up menu.
- When the window opens, double-click on the file to open the message in your e-mail client application.
- Read the message and if you agree that it is junk/spam/phishing then use the e-mail client's delete button to delete it (this is especially important when the word "Heuristics" appears in the infection name).
- If you disagree and choose to retain the message, return to ClamXav and choose "Exclude From Future Scans" from the pop-up menu.
- If this is a g-mail account and those messages continue to show up after you have deleted them in the above manner, you may need to log in to webmail using your browser, go to the "All Mail" folder, find the message(s) and use the delete button there to permanently delete them from the server.
To fix corrupted mailbox index(es), highlight each one that was corrupted and choose Rebuild from the appropriate menu.