Experts warn of possible attacks after PoC code for CVE-2018
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2017-5638 | Unauthenticated RCE in Apache Struts Jakarta Multipart parser CVE-2017-5638 is an improper input validation flaw (CWE-20) in the Jakarta Multipart parser of Apache Struts, in which the parser mishandles the Content-Type value of a file upload and allows malicious upload leading to remote code execution. It is triggered remotely without authentication by sending a crafted Content-Type header in a multipart request to a Struts endpoint; no valid upload or credentials are required. A successful attacker gains code execution in the security context of the application server, which typically enables host compromise, data theft, or ransomware deployment. Any organization running Apache Struts applications that use the Jakarta Multipart parser is affected; the provided data specifies only "Apache Struts" and gives no version ranges. Exploitation is confirmed in the wild: the flaw is listed in CISA KEV (added 2021-11-03) with known ransomware use, EPSS assigns it roughly a 100% exploitation probability (100th percentile), and no public PoC is catalogued in the source data. Do: Apply updates per vendor instructions: upgrade Apache Struts to the releases that fix this flaw (2.3.32 / 2.5.10.1 or later, per Apache advisory S2-045), and check for Struts jars bundled inside application packages and vendor appliances. Prioritize internet-facing apps, and as an interim mitigation validate or filter the Content-Type header on multipart requests. Because exploitation is in the wild and ransomware use is known, also review web and application server logs for evidence of successful compromise. | 9.8 | 100% | KEV ransomware PoC ×10 |
| masslikely hundreds of thousands of deployments (tens of thousands of Struts hosts were internet-exposed in public scans) | |
| CVE-2018-11776 | Apache Struts Remote Code Execution via Missing or Wildcard Namespace Apache Struts 2 contains an improper input validation flaw (CWE-20) that allows unauthenticated remote code execution when an attacker-controlled namespace (for example, part of the request URL path) is evaluated as an OGNL expression on the server. It is triggered under two circumstances: (1) the alwaysSelectFullNamespace option is true and a result defined in the configuration has no namespace while its parent package's namespace is unset or a wildcard, or (2) a URL tag in a template has no namespace under the same parent-package conditions. An attacker who can reach an application in one of these configurations gains arbitrary code execution with the privileges of the application server, so any organization running affected Struts 2 releases (2.3.7-2.3.34 and 2.5-2.5.16) in such configurations is exposed. CISA added the flaw to its Known Exploited Vulnerabilities catalog on 2021-11-03, confirming exploitation in the wild (ransomware use unknown), and EPSS currently assigns a 100% probability of exploitation within 30 days. CVSS is not yet scored in this feed, but the KEV listing and EPSS signal indicate urgent patching priority. Do: Upgrade Apache Struts to 2.3.35 or 2.5.17 (or later) on all applications, prioritizing internet-facing ones, per vendor instructions. If upgrading is not immediately possible, set alwaysSelectFullNamespace to false and ensure every result and URL tag specifies an explicit, non-wildcard namespace. Audit configurations, especially applications using the Convention Plugin or wildcard namespaces, for the vulnerable conditions and review web server logs for signs of OGNL injection in namespace values. | 8.1 | 100% | KEV PoC ×5 |
| massmillions of end users behind on the order of tens of thousands of internet-exposed Apache Struts deployments |
Full article585 words · extracted from securityaffairs.com · click to collapse
The Exploit code for the recently discovered Critical remote code execution vulnerability CVE-2018-11776 in Apache Struts 2 was published on GitHub, experts fear massive attacks.
The CVE-2018-11776 vulnerability affects Struts 2.3 through 2.3.34, Struts 2.5 through 2.5.16, and potentially unsupported versions of the popular Java framework.
“Possible Remote Code Execution when using results with no namespace and in same time, its upper action(s) have no or wildcard namespace. Same possibility when using url tag which doesn’t have value and action se” reads the security advisory published by Apache.
“Possible Remote Code Execution when using results with no namespace and in same time, its upper action(s) have no or wildcard namespace. Same possibility when using url tag which doesn’t have value and action set.”
Experts warn that it is possible to trigger the RCE flaw when namespace value isn’t set for a result defined in underlying XML configurations and at the same time, its upper action(s) configurations have no or wildcard namespace.
The flaw could be also exploited when using URL tag which doesn’t have value and action set and at the same time, its upper action(s) configurations have no or wildcard namespace.
According to the experts from Semmle that discovered the flaw, the vulnerability affects commonly-used endpoints of Struts, which are likely to be exposed.
“Attackers can attack vulnerable applications by injecting their own namespace as a parameter in an HTTP request. The value of that parameter is insufficiently validated by the Struts framework, and can be any OGNL string. OGNL (Object-Graph Navigation Language) is a powerful domain-specific language that is used to customize Apache Struts’ behavior,” the researcher explained.
An attacker could trigger the flaw by injecting his own namespace as a parameter in an HTTP request. The lack of proper validation for that parameter is the root of the problem.
Just two days after the Apache Software Foundation released their advisory a working proof-of-concept (PoC) was published online.
According to the experts from the threat intelligence firm Recorded Future, there is an intense activity related to the Struts flaw in a number of Chinese and Russian underground forums.
” Unfortunately, this makes the vulnerability trivial to exploit — in fact, proof-of-concept code has already been released, including a Python script that allows for easy exploitation. Recorded Future has also detected chatter in a number of Chinese and Russian underground forums around the exploitation of this vulnerability.” reads the analysis published by Recorded Future.
“Unlike last year’s Apache Struts exploit (CVE-2017-5638), which was at the center of the Equifax breach, this vulnerability appears easier to exploit because it does not require the Apache Struts installation to have any additional plugins running in order to successfully exploit it.”
Experts warn that the CVE-2018-11776 flaw is easier to exploit compared to the CVE-2017-5638 Apache Struts flaw that was exploited in the Equifax hack.
The number of potentially vulnerable application could be impressive.
“Apache Struts is a very popular Java framework and there are potentially hundreds of millions of vulnerable systems that could be exploited by this flaw. The challenge is in identifying how many systems are vulnerable.” continues Recorded Future.
“Because many of the servers running Apache Struts are backend application servers, they are not always easily identified, even by the system owners.”
The principal problem is that there are many reasons because Struts installs cannot be immediately updated especially in Critical systems.
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(Security Affairs – Apache Struts, CVE-2018-11776)
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Text extracted automatically; images, tables and formatting may be missing. Original: https://securityaffairs.com/75699/hacking/cve-2018-11776-struts-flaw-attacks.html