What is Dropbear SSH Vulnerability?
Vulnerabilities in Dropbear SSH Server Channel Concurrency Use-after-free Code Execution is a high risk vulnerability that is one of the most frequently found on networks around the world. This issue has been around since at least 1990 but has proven either difficult to detect, difficult to resolve or prone to being overlooked entirely.
| Vulnerability Name: | Dropbear SSH Server Channel Concurrency Use-after-free Code Execution |
| Test ID: | 14483 |
| Risk: | High |
| Category: | SSH Servers |
| Type: | Attack |
| Summary: | This vulnerability is located within the Dropbear daemon and occurs due to the way the server manages channels concurrency. A specially crafted request can trigger a `use after free` condition which can be used to execute arbitrary code under root privileges provided the user has been authenticated using a public key (authorized_keys file) and a command restriction is enforced (command option). $OUTPUT |
| Solution: | Upgrade to the Dropbear SSH version 2012.55 or newer. |
| CVE: | CVE-2012-0920 |
| More Information: | |
| Nist NVD (CVSS): | https://nvd.nist.gov/cvss |
| CVSS Score: | 7.1 |
Scanning For and Finding Vulnerabilities in Dropbear SSH Server Channel Concurrency Use-after-free Code Execution
Use of Vulnerability Management tools are standard practice for the discovery of this vulnerability. The primary failure of VA in finding this vulnerability is related to setting the proper scope and frequency of network scans. It is vital that the broadest range of hosts (active IPs) possible are scanned and that scanning is done frequently. We recommend weekly. Your existing scanning solution or set of test tools should make this not just possible, but easy and affordable. If that is not the case, please consider AVDS.
Dropbear SSH Server Penetration Testing
The Vulnerabilities in Dropbear SSH Server Channel Concurrency Use-after-free Code Execution is prone to false positive reports by most vulnerability assessment solutions. AVDS is alone in using behavior based testing that eliminates this issue. For all other VA tools security consultants will recommend confirmation by direct observation. In any case Penetration testing procedures for discovery of Vulnerabilities in Dropbear SSH Server Channel Concurrency Use-after-free Code Execution produces the highest discovery accuracy rate, but the infrequency of this expensive form of testing degrades its value. The ideal would be to have pentesting accuracy and the frequency and scope possibilities of VA solutions, and this is accomplished only by AVDS.
Security Updates on Vulnerabilities in Dropbear SSH Server Channel Concurrency Use-after-free Code Execution
Given that this is one of the most frequently found vulnerabilities, there is ample information regarding mitigation online and very good reason to get it fixed. Hackers are also aware that this is a frequently found vulnerability and so its discovery and repair is that much more important. It is so well known and common that any network that has it present and unmitigated indicates “low hanging fruit” to attackers.
Confirming the Presence of Vulnerabilities in Dropbear SSH Server Channel Concurrency Use-after-free Code Execution
AVDS is currently testing for and finding this vulnerability with zero false positives. If your current set of tools is indicating that it is present but you think it is probably a false positive, please contact us for a demonstration.
Patching/Repairing this Vulnerability
Vulnerabilities in Dropbear SSH Server Channel Concurrency Use-after-free Code Execution is a high risk vulnerability that is also high frequency and high visibility. This is the most severe combination of security factors that exists and it is extremely important to find it on your network and fix it as soon as possible.