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New Unsigned iertutil.dll

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#1 crazytrain86


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Posted 28 January 2015 - 07:56 AM

I came home yesterday to something odd. My VMWare crashed, and also I had my iertutil.dll file (previously signed by Microsoft) replaced by a different iertutil.dll that is NOT signed by Microsoft.
I submitted this dll to virustotal but received no hits on it (first submission ever): https://www.virustotal.com/en/file/ffe0114b9c5f0aa8cd7348b729e6c29a71fc97253889feb332ba2207373d638f/analysis/1422405560/
Similarly, Anubis had never seen this before: https://anubis.iseclab.org/?action=result&task_id=1302cd45f154eca94816cd504b0d06881
The file itself resides here: C:\Windows\SysWOW64\iertutil.dll
As of yesterday, this file was Microsoft signed. Today, the hash changed and it is no longer Microsoft signed (however it says Microsoft in the meta information). Also, this is the ONLY Microsoft dll in my SysWOW64 directory that is unsigned now (previously none). Can someone tell me if this is legit? If it is, why is it now unsigned and how did my computer change it? I have Microsoft update set to notify, but not auto install.

Edit: Topic moved from Windows 7 to the more appropriate forum. ~ Animal

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#2 iangcarroll


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Posted 28 January 2015 - 11:13 AM

This file is not signed on my Windows 8 machine, and I doubt we both have an infection. While my SHA256 hash doesn't match yours, we aren't running the same OS. I would suggest running an anti-malware tool to be sure.

Here's my VT link if you're interested.


edit: now that it's in the right section, I would run MalwareBytes. If it picks up anything, please paste the log but otherwise you should be good.

Edited by iangcarroll, 28 January 2015 - 06:00 PM.

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#3 crazytrain86

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Posted 29 January 2015 - 04:06 PM

Update: Today that iertutil.dll file was replaced with the original one (same hash, valid signed Microsoft). This does not seem like normal activity. Of note: The invalid one is actually "'(Not verified) Microsoft Corporation'", where the valid one is "(Verified) Microsoft Windows". Subtle difference, but might be meaningful.

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