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Jan Kopriva Profile
Jan Kopriva

@jk0pr

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Following
571
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392

Just one of the infosec crowd.

Between red team and blue team
Joined July 2019
Don't wanna be here? Send us removal request.
@jk0pr
Jan Kopriva
4 years
You may find links to new content I've published on https://t.co/mkRumnLeWW at @UntrustedNet.
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@sans_isc
SANS.edu Internet Storm Center
1 year
The strange case of disappearing Russian servers https://t.co/sCpjfUb6nb
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@UntrustedNet
Untrusted Network
1 year
Dnes jsem byl pozván do vysílání odpoledního Studia ČT 24, kde jsem odpovídal na otázky spojené s aktuálními výpadky spojenými s chybnou aktualizací pro senzory CrowdStrike Falcon pro Windows... https://t.co/rF7GFHceXB
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untrustednetwork.net
Dnes jsem byl pozván do vysílání odpoledního Studia ČT 24, kde jsem odpovídal na otázky spojené s aktuálními výpadky spojenými s chybnou aktualizací pro senzory CrowdStrike Falcon pro Windows, v...
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@jk0pr
Jan Kopriva
1 year
Few weeks ago, I came across a somewhat unusual phishing message that used a slight twist on the "reply-chain" theme to make it through e-mail filters. It is not new, but since I didn't find any write-ups of it anywhere, I wrote a short article, which you may find bellow...
@sans_isc
SANS.edu Internet Storm Center
1 year
"Reply-chain phishing" with a twist
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@sans_isc
SANS.edu Internet Storm Center
1 year
Support of SSL 2.0 on web servers in 2024
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@sans_isc
SANS.edu Internet Storm Center
2 years
It appears that the number of ICS accessible from the internet has risen by 30 thousand over 3 years
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@jk0pr
Jan Kopriva
2 years
It occurred to me that the current situation surrounding the xz-utils backdoor might present a good opportunity for a quick analysis to see if national or governmental CSIRTs/their host organizations/similar entities publish security advisories during holidays...
@sans_isc
SANS.edu Internet Storm Center
2 years
The xz-utils backdoor in security advisories by national CSIRTs
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@jk0pr
Jan Kopriva
2 years
An open redirect vulnerability exists in what remains of the Google Web Light service, and it is being actively exploited by threat actors in multiple phishing campaigns... #phishing #Google #vulnerable https://t.co/JzdNQusSPN
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untrustednetwork.net
An open redirect vulnerability exists in the remains of Google Web Light service, which is being actively exploited in multiple phishing campaigns. Google decided not to fix it, so it might be...
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@jk0pr
Jan Kopriva
2 years
Threat actors generally like to use legitimate third-party online services to host malicious content, since it makes their job significantly easier. And - unfortunately - even the Internet Archive is no exception in this regard...
@sans_isc
SANS.edu Internet Storm Center
2 years
Phishing pages hosted on https://t.co/PlDWCzNEma
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@sans_isc
SANS.edu Internet Storm Center
2 years
Computer viruses are celebrating their 40th birthday (well, 54th, really)
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@jk0pr
Jan Kopriva
2 years
The smallest and largest #malware samples that were "caught" by my e-mail trap in 2023 were a small (<2 kB) VBScript file and a very large (350 MB) EXE... And what might come as a surprise is, that these two samples were pretty much functionally identical.
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isc.sans.edu
Interesting large and small malspam attachments from 2023, Author: Jan Kopriva
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@sans_isc
SANS.edu Internet Storm Center
2 years
Phishing page with trivial anti-analysis features
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@jk0pr
Jan Kopriva
2 years
I was recently asked whether typos were still a useful indicator for identifying phishing messages. To answer this question, I wrote a short post, which was just published on the Internet Storm Center website...
@sans_isc
SANS.edu Internet Storm Center
2 years
Are typos still relevant as an indicator of phishing?
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@AlefSecurity
ALEF Security
2 years
Co se stalo v září?🤔 Novinkami a událostmi z kyberprostoru vás tradičně provedou @StanleyNovo a @jk0pr. Tentokrát se věnovali novinkám, jako: 👉Ransomware Útok na MGM a Caesars 👉Severokorejští Hackeři a Kyberloupež 👉Čína vs USA 👉Microsoftu Unikly Desítky TB Dat
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@jk0pr
Jan Kopriva
2 years
Last week, I came across an interesting phishing, in which a text with zero font size was used in quite a novel way in order to make the message appear more trustworthy. You may find details in the article linked below...
@sans_isc
SANS.edu Internet Storm Center
2 years
A new spin on the ZeroFont phishing technique
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@jk0pr
Jan Kopriva
2 years
A new Diary of mine was published today on the SANS Internet Storm Center website. In this one, we’ll take a look at a simple phishing which demonstrates quite well that the cost of committing cybercrime can unfortunately be extremely low…
@sans_isc
SANS.edu Internet Storm Center
2 years
The low, low cost of (committing) cybercrime
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@jk0pr
Jan Kopriva
2 years
One doesn't often find malware with 0 detections on VirusTotal, especially if it isn't completely new... Nevertheless, it seems I was “lucky” - a malicious batch file, which was used in a last week's phishing campaign I came across is still at zero… https://t.co/dUDYI2DTj1
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isc.sans.edu
From small LNK to large malicious BAT file with zero VT score, Author: Jan Kopriva
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@jk0pr
Jan Kopriva
2 years
It can be quite surprising to find out what devices accessible from the internet still support SSLv2. It seems that in Kazakhstan, where such devices are most common, over 166 thousand SSLv2-enabled devices are last-mile network boxes used by the largest national ISP...
@sans_isc
SANS.edu Internet Storm Center
2 years
Kazakhstan - world’s last SSLv2 superpower https://t.co/Vob4CY84aw
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@jk0pr
Jan Kopriva
3 years
Although SSLv2 is not completely "dead" yet, support for it seems to be dying off at a reasonable rate... Hopefully, this trend will continue in the futre.
@sans_isc
SANS.edu Internet Storm Center
3 years
After 28 years, SSLv2 is still not gone from the internet... but we're getting there https://t.co/5i8nKjOXWz
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@jk0pr
Jan Kopriva
3 years
I’m looking forward to this very much - if everything goes well, it should be a fun, relaxing talk for the attendees, even though we’re going to be talking about security… :)
@DevOpsDaysPrg
devopsdaysprague
3 years
🎯 Jan Kopriva is going to change the way you think about modeling threats, #secure #softwaredevelopment and analogies with small children or pets. Don't miss his ignite talk at #DevOpsDays Prague! #DevOps #SRE #cybersecurity #modelingthreats
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@jk0pr
Jan Kopriva
3 years
I came across a Facebook phishing campaign recently, which turned out to be quite interesting - one unusual aspect of it was that due to an incorrectly set "From" field, it appeared as if the sender didn't have an e-mail address...
@sans_isc
SANS.edu Internet Storm Center
3 years
Ongoing Facebook phishing campaign without a sender and (almost) without links https://t.co/IAHlY2Z0LJ
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