Re: Malicious Chrome Extensions

["Stanwyck, Carraig - ASOC - Kansas City, MO" <Carraig.Stanwyck () asoc usda gov>]

I just wanted to follow up...

The published rule has already caught another malicious extension from a different domain that I included in the 
original text file of suspected domains, so it appears my suspicious were correct.  That said, I still have little 
information.  We have identified 3 infected hosts, but were only able to retrieve the extensions list on one of the 
machines.  Once the extensions were cleared, the traffic stopped.  That said, I haven't identified the malicious 
extension.

Installed Extensions on Infected Host:

-          Amazon Assistant for Chrome

-          Ambient Aura

-          Chromarks - Chrome Bookmarks Menu

-          Extensions Manager (aka Switcher)

-          Fair AdBlock (by STANDS)

-          Fair Adblock App (by STANDS)

-          Fair Ads (by STANDS)

-          Google Cast

-          Google Chrome to Phone Extension [DEPRECATED]

-          Google Contacts Launcher

-          Google Docs Offline

I haven't found anything malicious on these when researching them, but your move may vary.  Deleting them all stopped 
the malicious traffic.

Regards,
Carraig Stanwyck
USDA | OCIO | ASOC



From: Stanwyck, Carraig - ASOC - Kansas City, MO [mailto:Carraig.Stanwyck () asoc usda gov]
Sent: Friday, August 05, 2016 7:32 AM
To: emerging-sigs () lists emergingthreats net; snort-sigs () lists sourceforge net
Cc: Clemons, Matt - OCIO-ASOC, Kansas City, MO <matt.clemons () asoc usda gov>
Subject: [Snort-sigs] Malicious Chrome Extensions

Good Morning,

I have identified what I am almost certain is traffic from malicious chrome extension infections on our network.  The 
IOC in my case is hxxp://brainlog.top, which has the same registrar (VIACHESLAV ZINKEVICH) as 100+ other suspicious 
domains (attached), including 4chan-plus.com, which has a reddit PSA 
(https://www.reddit.com/r/chrome/comments/4caqdv/psa_remove_4chan_plus_its_inserting_malware_into/) for the same 
activity we're seeing here.

Proposed rule:
alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"ET MALWARE Malicious Chrome Extension"; 
flow:established,to_server; content:"page?url="; http_uri; fast_pattern; content:"user"; http_uri; content:"iframe="; 
http_uri; content:!"Referer|3a|"; http_header; classtype:trojan-activity; sid:123456; rev:1; )

It'd be pretty easy to add some pcre into it if necessary, the patterns are consistent.

Example URIs (2 separate infections, delineated by the string following "user"):
/user/bnd17qvgs0r4693lekp8mj52hwazxocf/318782/page?url=https://www.groupon.com/deals/k-f-custom-car-detailing&iframe=
/user/bnd17qvgs0r4693lekp8mj52hwazxocf/318782/page?url=https://www.indiemerch.com/&iframe=
/user/bnd17qvgs0r4693lekp8mj52hwazxocf/318782/page?url=https://www.indiemerchstore.com/&iframe=
/user/e43tohsduglaic1qnk5896fmyzjrbv0p/39344/page?url=https://www.full30.com/&iframe=
/user/e43tohsduglaic1qnk5896fmyzjrbv0p/39344/page?url=https://www.google.com/&iframe=
/user/bnd17qvgs0r4693lekp8mj52hwazxocf/318782/page?url=http://l.instagram.com/?e=ATNv0z315R1OmkaGMEZAoaq-DKaekIneFy9u3I5gbf9ileNm211AFFAd&u=http%3A%2F%2Fwww.mixcloud.com%2Fdjhomeschool&iframe=
/user/bnd17qvgs0r4693lekp8mj52hwazxocf/318782/page?url=http://money.cnn.com/2016/08/02/news/economy/donald-trump-hillary-clinton-facebook/index.html&iframe=
/user/bnd17qvgs0r4693lekp8mj52hwazxocf/318782/page?url=http://www.cnn.com/2016/08/03/europe/leopard-cubs-twycross/index.html&iframe=

Thanks,
Carraig Stanwyck
USDA | OCIO | ASOC
@C4RR41G





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