23 September 2018
For some weeks now I am busy with patch strategy and vulnerability management. When new critical vulnerabilities shows up two questions must be addressed:
- How fast must we patch the vulnerable systems?
- What vulnerabilities must be patched with highest priority? Or mitigated, if a patch is not available in due time.
Speed is the key in cyber security. The faster we find and patch vulnerable systems the greater is the chance that cyber criminals cannot exploit the vulnerabilities.
The exploit is the weapon in cyber warfare. A vulnerability as such increases the potential risk only. Once an exploit is published that can leverage the vulnerability, the vulnerability becomes a real risk. And if the exploit is “in the wild”, i.e. if the exploit is actively used by cyber criminals for attacks, the IT organization is on red alert.
Unfortunately, no one knows when an exploit spreads in the wild. Therefore, the cautious answer to the above questions is:
“The moment an exploit for a critical vulnerability is published it must be patched directly, at least on critical systems. If a patch is not available proper protective measures must be applied to mitigate the risk effectively.”
Browsers are the most critical systems because they are used in a hostile environment. Browsers are very complex applications, thus prone of errors. Between 2013 and 2017 about 11% of 40671 vulnerabilities in total were found in the 4 major browsers Chrome, Firefox, Internet Explorer and Edge.
It remarkable to see that 67% of all browser vulnerabilities are related to IE, Edge and Firefox although they have only a small market share (11% in 2017).
The graphic above shows the number of exploits that are published within one month before the CVE is published compared to the number of exploits published within one month after the CVE is published.
Except for Chrome and Firefox the majority of exploits is published after the vulnerability is published. Nevertheless, we have to patch immediately on publication of a CVE.
How many exploits spread in the wild? This question is hard to answer. The Symantec attack signatures give a useful indication. “An attack signature is a unique arrangement of information that can be used to identify an attacker’s attempt to exploit a known operating system or application vulnerability.”
This is an amazing result, isn’t it.
Have a great week!
- NIST. NVD Database. https://nvd.nist.gov/
- Offensive Security. Exploit Database. https://www.exploit-db.com
- Andrea Fioraldi. CVE Searchsploit.
- NIST. EXPLOIT-DB Reference Map. http://cve.mitre.org/data/refs/refmap/source-EXPLOIT-DB.html
- Symantec.com. Attack Signatures. https://www.symantec.com/security_response/attacksignatures/