At the close of each year we see at least one article covering the top vulnerabilities / exploits from the prior year. This is usually written on the back of having large detection networks across the Internet that get a comprehensive view of exploitation. It’s a great way to get real intelligence for criminal hacking activity. Unfortunately, we often see a breakdown when it comes to conveying that information in a useful manner. I know there is an argument to be made that the companies releasing such blogs are primarily after PR, sure. But they also have an opportunity to help their clients and the rest of the world by ensuring the blogs contain more useful and actionable information.
For this commentary, I’ll examine Radware’s blog, “The Top Web Service Exploits in 2020” published December 23, 2020 and covered almost verbatim by Security Magazine on January 5, 2021. I don’t have a view into exploit activity itself, but I do have a good view into the vulnerability disclosure landscape that is a cornerstone of this commentary.
We’ll start by setting a few basic ideas for mutual understanding for any such blog. First, each exploit should be tied to a unique vulnerability or it should explain it is an exploit chain and clearly delineate each vulnerability in the chain or explain what it represents if not a pure vulnerability. Second, it should provide at least one external reference for each vulnerability; either a CVE ID, vendor advisory, or commonly accepted third-party advisory such as US-CERT or another similar body. This is what allows the reader to quickly determine if their organization has patched against the vulnerability or not. If I have to spend considerable time trying to determine which vulnerability is being described, many organizations may be at a complete loss trying to figure it out.
With that, let’s look at the top 10 exploited vulnerabilities in 2020, according to Radware, and try to figure out some additional information for perspective. I will also be very clear that Radware’s blog is extremely frustrating and not immediately helpful, instead requiring a lot of extra work. The fact that they only attributed three exploits to a CVE ID is a dismal commentary on the CVE ecosystem. This analysis of their analysis will server as a reminder that comprehensive vulnerability intelligence is the foundation of any good security program.
Service Exploit #1: /ws/v1/cluster/apps/new-application
Based on their description, this appears to match VulnDB 184750 “Apache Hadoop YARN ResourceManager REST API Request Handling Remote Command Execution“. The first thing of interest is it was disclosed on October 19, 2016 and does not have a CVE assignment over four years later. No wonder many organizations aren’t aware of this vulnerability and have not sought out their own remediation strategy.
Service Exploit #2: /manager/html
This is summarized as “Apache Tomcat Manager Application Upload Authenticated Code Execution” and goes on to describe it as “This module can be used to execute a payload on Apache Tomcat servers that have an exposed “manager” application. The payload is uploaded as a WAR archive containing a JSP application using a POST request against the /manager/html/upload component.“
Despite this description, that does not cleanly map to any vulnerability in VulnDB. The closest matches are CVE-2017-12615 and CVE-2017-12617 which is an abstraction for different platforms, but fundamentally “Apache Tomcat HTTP PUT Method JSP File Upload Remote Code Execution“. On the surface this is a match with Apache Tomcat, JSP application, and POST request to achieve code execution. However, those two CVEs cover a JSP file upload, not a WAR archive, and do not mention the /manager/html/upload component. So we’re left wondering if the exploit described is simply a misconfiguration scenario (i.e. intended functionality not secured) or an actual disclosed vulnerability.
Service Exploit #3: /level/15/exec/-/sh/run/CR
Based on the description, this is a misconfiguration scenario where an administrator sets up a Cisco router with the HTTP admin interface enabled, but without password protection. This allows an attacker to use the legitimate functionality to run arbitrary commands.
Service Exploit #4: /admin/assets/js/views/login.js
Radware says this “resource belongs to Sangoma FreePBX code and it looks like the attackers are trying to detect vulnerable FreePBX servers and exploit one of the known vulnerabilities.” The first issue is that script doesn’t immediately track to a VulnDB entry based on titles, which reflect the script name typically. However, let’s consider the URL being seen: … login.js. Rather than attempting to exploit “one of the known vulnerabilities“, I would suggest instead they are trying default credentials. At least back around 2000, the tried-and-true default credentials of admin/admin were all you needed to access the interface.
This one is curious to me because presumably a company that was detecting exploit traffic and could see e.g. POST requests as demonstrated in Service Exploit #2, would also see that the attackers were trying the default credentials. So we’re left with Service Exploit #4 being of little help and only creating confusion over what is being exploited.
Service Exploit #5: /ftptest.cgi?loginuse=&loginpas=
Radware attributes this to “many cheap Wireless IP web cameras use the same genetic code based on the GoAhead code (the tiny, embedded web server).” This tracks cleanly with VulnDB 181032 “Axis Multiple Products axis-cgi/ftptest.cgi Multiple Parameters Remote Command Execution Weakness“. This is actually a fun rabbit hole as this disclosure originally comes from an audit of a AXIS A1001 Network Door Controller and exploitation of this issue requires privileged access to the management interface. With that in mind, we’re back to a default credential scenario that may be the actual issue. Back in 2001, defaults for Axis network cameras were covered by CVE-2001-1543.
[Update: Z Balazs points out that this finding is likely due to Persirai botnet activity and links to more information.]
Service Exploit #6: /service/extdirect
This is the only one of the ten exploits covered that they include a CVE ID for. CVE-2019-7238 maps to VulnDB 198437 “Nexus Repository Manager /service/extdirect Insufficient Access Control Request Handling Remote Code Execution“. But, is that really the right ID? If we look at CVE-2020-10204 we are given a very brief summary of “Sonatype Nexus Repository before 3.21.2 allows Remote Code Execution” and a link to the vendor advisory. However, VulnDB 226228 also maps to this and is summarized as “Nexus Repository Manager /service/extdirect Request Handling Remote Command Execution“. We immediately see the /service/extdirect from Radware’s finding in both titles. The vendor’s advisory does not include this endpoint though, but we find it in this exploit published on GitHub that tracks with the CVE-2020-10204 and we see it in a different exploit for CVE-2019-7238.
CVE-2019-7238 was fixed in Nexus Repository Manager version 3.15.0 and CVE-2020-10204 was fixed in version 3.21.2. Due to the vague vendor advisories it difficult to tell if this was a regression situation or something else. But, the CVE-2020-10204 vendor advisory gives us the interesting bit in the context of exploitation: “The vulnerability allows for an attacker with an administrative account on NXRM to execute arbitrary code by crafting a malicious request to NXRM.” That is an important distinction! So this is likely CVE-2019-7238 as Radware says, unless there are default credentials which would allow for exploiting CVE-2020-10204 as well.
Looking at the NVD entry for CVE-2020-10204 we also see that they scored this incorrectly for their CVSSv3 score, as ‘Privileges Required‘ should be ‘High‘, not ‘Low‘ as they have it.
Service Exploit #7: /solr/admin/info/system?wt=json
For this one, we get an Apache Bug ID (SOLR-4882) and CVE-2013-6397 as references which is great. That said, it would be very helpful if Radware would link to these resources to make it easier for their readers.
Service Exploit #8: /vendor/phpunit/phpunit/src/Util/PHP/eval-stdin.php
This is the third exploit they match to an ID, CVE-2017-9841 and it was disclosed June 27, 2017. Another good reminder that software with disclosed vulnerabilities and vendor solutions are not being applied, causing many organizations to become low-hanging fruit in the exploit world.
One little nitpick is that the full path they include is likely not how this would manifest on a server. Everything after “src” would be the endpoint being scanned presumably: /Util/PHP/eval-stdin.php
Service Exploit #9: /hudson
With this, we run into another mess and rabbit hole. Radware summarizes this as “Hudson continuous integration tool – multiple vulnerabilities” and further describes Hudson as “a continuous integration tool written in Java, which runs in a servlet container, such as Apache Tomcat or the GlassFish application server. Over the years the project was replaced by Jenkins. The final release. 3.3.3 was on February 15, 2016. Today Hudson is no longer maintained and was announced as obsolete in February 2017.“
Based on this description, this could be any one of at least 50 vulnerabilities going back to February, 2014, one of which does not have a CVE ID. 41 of these are in Jenkins software which is mentioned above.
Other Service Exploits
This is a curious conclusion to the “top 10” list, as it states “In addition to the new items that we covered in this list, we have also seen items that we already saw and covered in our previous blog Top 10 Web Service Exploits in 2019 such as /ctrlt/DeviceUpgrade_1, /TP/public/index.php and /nice%20ports%2C/Tri%6Eity.txt%2ebak.“
That isn’t exactly a #10 on this list, rather a catch-all for “other stuff we saw including…“. The first listed tracks with VulnDB 170573 “Huawei HG532 Routers /ctrlt/DeviceUpgrade_1 NewStatusURL Element Remote Command Execution (Satori)” which is notable as it is used in Satori, a Mirai botnet variant.
The second tracks with VulnDB 194379 “ThinkPHP /public/index.php call_user_func_array() Function vars Parameter Remote Code Execution“. Note the different exploit path and we see it can actually be exploited via several endpoints according to analysis of the vulnerability by Knownsec 404 Team.
The third doesn’t immediately track with an entry in VulnDB. Radware gives us “/nice%20ports%2C/Tri%6Eity.txt%2ebak” which we can decode to a more friendly “/nice ports,/Trinity.txt.bak“. A quick Google for that request finds a blog from Dragos titled “Threat Hunting With Python Part 2: Detecting Nmap Behavior with Bro HTTP Logs” explaining this request:
The request for “/nice ports,/Trinity.txt.bak” comes from Nmap’s service detection routine testing how a server handles escape characters within a URI. The actual request is “GET /nice%20ports%2C/Tri%6Eity.txt%2ebak HTTP/1.0\r\n\r\n”.
So this isn’t an actual exploit, rather, it indicates that attackers are using the Nmap port scanner. This is a good reminder that “exploit scanning” doesn’t always cleanly map to a specific vulnerability.
Detecting exploitation is critical for every organization. Doesn’t matter if it is on-premises devices or a managed service-based detection. What is more critical is having comprehensive and timely vulnerability intelligence that can turn what you detect into actionable information. This is how you not only detect, but evaluate and remediate, assuming of course the vulnerability is known to the vendor or a mitigation can be enacted.