# What is CVE-2018-16115? > CVE-2018-16115 is a critical-severity flaw (CVSS 9.1) in Akka from Lightbend, published on 29 August 2018. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 1.2%. If you run an affected version, plan in the vendor’s fix. Canonical page: https://www.precursorintelligence.com/what-is/cve-2018-16115 ## At a glance - **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month. - **Precursor Intelligence risk score:** 54 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes. - **Severity:** Critical (CVSS 9.1 out of 10) - **Known to be exploited:** No, not on the list of flaws known to be exploited today - **Chance of use in the next 30 days:** 1.2% (latest exploit-likelihood forecast) - **Published:** 29 August 2018 - **Record last updated:** 8 November 2018 - **Main product:** Akka from Lightbend - **Affected products:** 1 ## What is CVE-2018-16115? In plain terms It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data and change data. ### The official description Lightbend Akka 2.5.x before 2.5.16 allows message disclosure and modification because of an RNG error. A random number generator is used in Akka Remoting for TLS (both classic and Artery Remoting). Akka allows configuration of custom random number generators. For historical reasons, Akka included the AES128CounterSecureRNG and AES256CounterSecureRNG random number generators. The implementations had a bug that caused the generated numbers to be repeated after only a few bytes. The custom RNG implementations were not configured by default but examples in the documentation showed (and therefore implicitly recommended) using the custom ones. This can be used by an attacker to compromise the communication if these random number generators are enabled in configuration. It would be possible to eavesdrop, replay, or modify the messages sent with Akka Remoting/Cluster. ### What kind of flaw is it? - CWE-338: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) ### How an attack on it works - Where an attacker can be: Anywhere on the internet - How hard it is to pull off: Easy: no special conditions - Login needed first: No login needed - Does someone have to click: No, nobody has to do anything - What an attacker gets: Can read data and change data Severity vector: `CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N` ## Is CVE-2018-16115 being exploited? Not that we know of It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 1.2%. That can change at any time, which is why we keep watching. Exploit likelihood over the last 7 days: 1.2%, 1.2%, 1.2%, 1.2%, 1.2%, 1.2%, 1.2%. ### Timeline - 29 August 2018: Published - 8 November 2018: Record last updated ### How Precursor Intelligence ranks it CVE-2018-16115 scores **54 out of 100 (Medium)**, with the action "Plan remediation". Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less: - Evidence it is being exploited: biggest factor - How severe it is: strong factor - How widely exposed it is: smaller factor - Threat activity around it: smaller factor 85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it. ## Who is affected by CVE-2018-16115? The published record lists 1 product. Versions are as published: "2.5.0 to before 2.5.16" means from 2.5.0 up to, but not including, 2.5.16. - [Akka](https://www.precursorintelligence.com/product/lightbend/akka) by [Lightbend](https://www.precursorintelligence.com/vendors/lightbend) (Application): 2.5.0 to before 2.5.16 ## How do I fix CVE-2018-16115? 1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list. 2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list. 3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in. 4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood. ### References - [doc.akka.io](https://doc.akka.io/docs/akka/current/security/2018-08-29-aes-rng.html) (Vendor advisory) ## Questions ### What is CVE-2018-16115? CVE-2018-16115 is a critical-severity flaw in Akka from Lightbend, published on 29 August 2018. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data and change data. ### How serious is CVE-2018-16115? It scores 9.1 out of 10 on the CVSS severity scale, which is critical. Our risk score for CVE-2018-16115 is 54 out of 100, which is Medium. Its action is "Plan remediation". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month. ### Is CVE-2018-16115 being exploited? It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 1.2%. That can change at any time, which is why we keep watching. ### Which versions does CVE-2018-16115 affect? For Akka from Lightbend: 2.5.0 to before 2.5.16. ### How do I fix CVE-2018-16115? Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. ## Does CVE-2018-16115 affect you? Precursor Intelligence keeps checking for you: - **Tell us what you run.** Pick your software from a list, or let us work it out from your website. - **We match it to every flaw.** Over 400,000 published flaws, checked against your list. - **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it. - **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools. Start free (no card, nothing to install): https://www.precursorintelligence.com/register Book a demo: https://www.precursorintelligence.com/contact