Sensor Intel Series: Top CVEs in November 2022

The Sensor Intel Series is created in partnership with Efflux , who maintains a globally distributed network of sensors from which we derive attack telemetry.

It is time for another monthly round-up of web scanning and attack telemetry from our data partners Efflux. As usual, we focus on ports 80 and 443. It's been said for a long time that new services will increasingly use HTTP/TLS as their transport protocol, which is certainly true, especially as web API becomes a dominant way to provide services.

It's worth noting, however, that there is nothing inherent in those protocols that require them to be run on port 80 or 443. Indeed, many IoT devices, "private/internal" services, and proxies run webservers on alternate ports and are not therefore included in our analysis. Yet, we know that scanners are looking for HTTP/TLS services on alternate ports as well, and this should be a factor in any risk assessment.

November Vulnerabilities By the Numbers

Figure 1 shows the attack or scan traffic for the top ten vulnerabilities in November. In this view, the difference between CVE-2020-8958 and the other vulnerabilities this month is notable.

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Figure 1. Top ten vulnerabilities by traffic volume during November 2022. CVE-2020-8958, an IoT OS command injection vulnerability, received nearly double the amount of attack traffic as the next vulnerability down, CVE-2018-13379.

Even a single exploit attempt against a vulnerable system can be devastating, however, so Table 1 shows the attack volume and change from October for all 40 of the vulnerabilities that were targeted in November.

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Table 1. CVE targeting volume for November, along with traffic change from October.

Targeting Trends

To understand how attacker attention evolves over time, Figure 2 shows changes in rank and attack volume for the most heavily targeted vulnerabilities. The eleven vulnerabilities plotted here represent the top five per month across all eleven months, since plotting all 49 tracked CVEs would be impossible to decipher.

Figure 2. Evolution of vulnerability targeting, January - November 2022. Compared with October, there was no significant change, with all of the top five targets remaining consistent in rank.

Figure 2 makes it easy to see the comparative stability in attacker traffic between October and November, with the top five CVEs remaining consistent in rank. With the exception of CVE-2020-8958, which grew in traffic by nearly 50% in November, they also stayed roughly consistent in terms of attack volume.

Identifying Rapid Growth

Figure 3 shows the traffic over 2022 for all 49 vulnerabilities, ranked in order of total number of connection attempts from January to November. As discussed in the September and October SIS, this plot makes it easy to spot dramatic changes in attacker attention, as we see in CVE-2022-22947 in April and CVE-2017-18368 in March.

Figure 3. Plot of all 49 tracked CVEs over time. Note log10 scale on y axes.

Another interesting aspect of Figure 3 is identifying when vulnerabilities drop off for periods of time. In October we identified two recently released vulnerabilities, CVE-2022-40684 and CVE-2022-41040, in our logs. Both are severe vulnerabilities; CVE-2022-40684, an authentication bypass vulnerability in various Fortinet security appliances, has a CVSS 3.1 score of 9.8,¹ and CVE-2022-41040, an escalation of privilege vulnerability in Microsoft Exchange Server, has a CVSS 3.1 score of 8.8.³ (https://www.f5.com/labs/articles/threat-intelligence/sensor-intel-series-top-cves-november-2022#_ftnAutoIncr3) CVE-2022-41040, the Exchange Server vulnerability, did not recur in our logs in November (which is good news), whereas CVE-2022-40684 increased in volume by nearly 80 percent (bad news). Owners of vulnerable Fortinet systems should take note and patch aggressively due to this growth in interest. We note that while attention on the other significant Fortinet vulnerability here, CVE-2018-13379, was nearly sixfold the traffic looking for CVE-2022-40684, CVE-2018-13379 is beginning to decline in prominence, so if the current trends continue, the more recent Fortinet vulnerability will eventually supersede it.

Conclusions

As ever, the number one conclusion from the Sensor Intel Series remains constant: patch if you’re vulnerable. Even the low-traffic vulnerabilities on this list have a demonstrated amount of attacker intent, which places them in the minority of vulnerabilities.

Furthermore, significant growth in CVE-2020-8958, alongside the recent addition of CVE-2014-2908 to our logs, should serve as a reminder about the relationship between IoT vulnerabilities and botnets for DDoS. This means that there is another recommendation for all organizations, irrespective of whether their footprint contains any of these vulnerabilities: plan for future DDoS attacks.