[2023 kcdc] cve 101: the unfolding of a zero day attack

Speaker: Theresa Mammarella

Twitter: @t_mammarella

For more, see the table of contents.


  • Annual cost of cyber crime predicting to top 8 trillion. Only US and China have more than that as GDP


  • Vulnerability – weakness/flaw in system
  • Threat – attack vector, potential action
  • Risk – probably frequency of that loss.
  • Goal of cybersecurity is to minimize risk. Can’t control intent to do harm so focus on vunlerability


  • CVE – Common Vulnerabilities and Exposures
  • Format CVE-xxxx-yyyyy. xxxx = year came out. yyyy = identifier
  • CVSS scoring – how bad is it on a scale of 0-10. Ten is worst
  • CVSS score has three parts – basic (exploitability, impact), temporal, environmental. Good description here
  • Basic is the one we see on the CVE
  • CVE can be rejected. The number is used and cannot be reused. Example. Something thought found a vulnerability. Investigation was flawed and not an actual issue. Story about it here.

How to talk about

  • Private disclosure – organization can choose when/whether to fix/share
  • Coordinated/responsible disclosure – best practice – agreed upon time frame
  • Full/public disclosure – share everything
  • Best to report via company website, security.md file, security files on server, github private vulnerability reporting

Zero day vulnerability


  • log4jshell – remote code loading. Was reported responsibility but incomplete fix so zero days on those CVEs
  • Could be as simple as a bounds check. For OpenSSL. Announced something big coming and get ready. When announced learned it only affected OpenSSL 3 (not 2) and high, not critical so boy who cried wolf situation.

Security Practices for Developers

  • Insider threat includes poor training
  • A lot more developers than info security. Increasingly harder for security teams to keep up.
  • Cost of finding and fixing bugs increases over time
  • Does this touch the internet? take untrusted input/ handle sensitive data?
  • OWASP Top 10. Updated in 2021 to add insecure design, software/data integrity failures and server side request forgery (SSRF). Some merged such as injection.
  • Starting OWASP Top 10 for Large Language Model Applications. A draft version is available
  • mitre/hipcheck – scorecard for supply chain risk. Similarly, Sonatype security rating and OpenSSF Scorecard
  • Open source dependency management. Embedded in many projects. 90% of app is open source on average. North Korea attacked many apps including Putty

Attack types

  • Typosquatting – look alike domain with one or two wrong characters
  • Open source repo attackes – attempt to get maleware/weakness added into depednecy source
  • Build tool attacks
  • Dependency confusion – different version that shows up as latest


  • Sometimes third party projects. ex: OpenSSF Scorecard
  • NPM and PyPI often have supply chain attacks. Maven Central more so
  • Scanning tools to find issues can be helpful
  • You are responsible when things go wrong

My take

Good talk. Covered concepts and good real life examples. I learned a few things like the OWASP Top 10 for LLMs. Appreciated the shout out to “the Java people in the front row” when talking about log4j. I added a few links in my blog that weren’t in the original presentation for things I wanted to learn more about.

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