PoshC2 false positive

[MichaelWrigh]

Hello,

We are seeing what appears to be false positive detections for the PoshC2C vulnerability signatures that was released recently. Connections going to Google and BBC, is anyone else seeing the same thing here?

[lvultao]

I think I'm seeing this too. I have a particular user where I'm seeing this when they click the google logo to go back to the main search page. I'm getting Threat ID: 86523

[Adrian_Jensen]

Confirmed. I just tried the same and got the alert for PoshC2 (ThreatID: 86523, release 8540 2022-03-10). Extremely easy to replicate:

1) Do a Google search

2) Click the Google logo on the search results page

3) Page redirects to hxxps://google.com/webhp?hl=en&sa=X&ved=<trackingID> and is blocked as a threat

[SecurityEngineering]

It appears that the rule looks for the URL strings listed on github[.]com/johnjohnsp1/PoshC2_Python/blob/master/Config.py:

URLS = '"adsense/troubleshooter/1631343/","adServingData/PROD/TMClient/6/8736/","advanced_search?hl=en-GB&fg=","async/newtab?ei=","babel-polyfill/6.3.14/polyfill.min.js=","bh/sync/aol?rurl=/ups/55972/sync?origin=","bootstrap/3.1.1/bootstrap.min.js?p=","branch-locator/search.asp?WT.ac&api=","business/home.asp&ved=","business/retail-business/insurance.asp?WT.mc_id=","cdb?ptv=48&profileId=125&av=1&cb=","cis/marketq?bartype=AREA&showheader=FALSE&showvaluemarkers=","classroom/sharewidget/widget_stable.html?usegapi=","client_204?&atyp=i&biw=1920&bih=921&ei=","load/pages/index.php?t=","putil/2018/0/11/po.html?ved=","q/2018/load.php?lang=en&modules=","status/995598521343541248/query=","TOS?loc=GB&hl=en&privacy=","trader-update/history&pd=","types/translation/v1/articles/","uasclient/0.1.34/modules/","usersync/tradedesk/","utag/lbg/main/prod/utag.15.js?utv=","vs/1/vsopts.js?","vs/site/bgroup/visitor/","w/load.php?debug=false&lang=en&modules=","web/20110920084728/","webhp?hl=en&sa=X&ved=","work/embedded/search?oid="'

[Adrian_Jensen]

---

@SecurityEngineering wrote:

  "webhp?hl=en&sa=X&ved="

---

Bingo.... that is the path of the Google redirect back to the main search page.

@MichaelWrigh  Have you opened a false alert report with PA?

[MichaelWrigh]

Not yet, am hoping to get it done soon though. Am on a training course this week but should be bale to find the time.

[Adrian_Jensen]

It looks like someone has already submitted a false positive report. The 8541 release has a single note about improving PoshC2 detection. Testing against Google I am no longer seeing the false alert.