Text4Shell, an RCE bug in Apache Commons Text library
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2021-44228 | JNDI Injection Remote Code Execution in Apache Log4j2 (Log4Shell) Apache Log4j2, an extremely widely used Java logging library, fails to protect its JNDI lookup feature against attacker-controlled JNDI-related endpoints (CWE-20, CWE-502), so crafted text processed by the logger causes the Java runtime to fetch and load attacker-supplied objects, leading to remote code execution. The flaw is triggered whenever attacker-controlled input reaches the logging API and is parsed for JNDI lookups, a pattern common in web servers and enterprise Java applications that log user-supplied fields such as headers or form values. Successful exploitation yields arbitrary code execution under the privileges of the affected application, giving attackers a foothold for lateral movement, data theft, and ransomware deployment. Any Java application or product that ships or bundles an affected Apache Log4j2 release is exposed, making this one of the most broadly deployed vulnerabilities ever disclosed. Exploitation is confirmed in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2021-12-10 with known ransomware use, and EPSS assigns a 100% probability of exploitation within 30 days. Do: Inventory all Java applications and dependencies for Apache Log4j2 and apply the vendor's patched updates, or remove affected assets from the network, as required by CISA's KEV catalog. Where updates are not yet available, use the temporary mitigations in CISA's ED-22-02 recommended-mitigation guidance, such as disabling message lookups, only until patches are applied. Prioritize internet-facing and business-critical systems and hunt for exploitation activity given known ransomware use. | 10.0 | 100% | KEV ransomware PoC ×9 |
| masshundreds of millions of Java applications/devices, with hundreds of thousands of internet-exposed services | |
| CVE-2022-42889 | Apache Commons Text performs variable interpolation, allowing properties to be dynamically evaluated and expanded. Apache Commons Text performs variable interpolation, allowing properties to be dynamically evaluated and expanded. The standard format for interpolation is "${prefix:name}", where "prefix" is used to locate an instance of org.apache.commons.text.lookup.StringLookup that performs the interpolation. Starting with version 1.5 and continuing through 1.9, the set of default Lookup instances included interpolators that could result in arbitrary code execution or contact with remote servers. These lookups are: - "script" - execute expressions using the JVM script execution engine (javax.script) - "dns" - resolve dns records - "url" - load values from urls, including from remote servers Applications using the interpolation defaults in the affected versions may be vulnerable to remote code execution or unintentional contact with remote servers if untrusted configuration values are used. Users are recommended to upgrade to Apache Commons Text 1.10.0, which disables the problematic interpolators by default. NVD description · AI analysis pending | 9.8 | 100% |
| — |
Full article543 words · extracted from securityaffairs.com · click to collapse
Researcher discovered a remote code execution vulnerability in the open-source Apache Commons Text library.
GitHub’s threat analyst Alvaro Munoz discovered a remote code execution vulnerability, tracked as CVE-2022-42889, in the open-source Apache Commons Text library. Apache Commons Text is a library focused on algorithms working on strings.
The vulnerability, dubbed “Text4Shell,” is an unsafe script evaluation issue caused by the interpolation system. An attacker can exploit the flaw to trigger code execution when processing malicious input in the library’s default configuration.
“The StringSubstitutor when used with the default interpolators (StringSubstitutor.createInterpolator()) will perform string lookups that may lead to arbitrary code execution.” reads the post published by Munoz. “In particular, if untrusted data flows into the StringSubstitutor.replace() or StringSubstitutor.replaceIn() methods, an attacker will be able to use the ScriptStringLookup to trigger arbitrary code execution.”
The Apache Commons Text relies on the interpolation system to manipulate strings.
The developer Gary D. Gregory reported that starting with version 1.5 and continuing through 1.9, the set of default Lookup instances included interpolators that could result in arbitrary code execution or contact with remote servers.
“These lookups are: – “script” – execute expressions using the JVM script execution engine (javax.script) – “dns” – resolve dns records – “url” – load values from urls, including from remote servers Applications using the interpolation defaults in the affected versions may be vulnerable to remote code execution or unintentional contact with remote servers if untrusted configuration values are used.” wrote the developer in the Apache mailing list.
The issue was addressed with the release of Apache Commons Text 1.10.0, which disables the problematic interpolators by default.
Some experts compared to Log4Shell since it is an open-source library-level vulnerability that is likely to impact a wide variety of software applications that use the relevant object. However, initial analysis indicates that this is a bad comparison. The nature of the vulnerability means that unlike Log4Shell, it will be rare that an application uses the vulnerable component of Commons Text to process untrusted, potentially malicious input.
The vulnerability has been compared Text4Shell to Log4Shell due to its potential impact on a large number of applications that uses the library. However Rapid7 researchers downplayed the impact of the flaw in the wild.
“The vulnerability has been compared to Log4Shell since it is an open-source library-level vulnerability that is likely to impact a wide variety of software applications that use the relevant object. However, initial analysis indicates that this is a bad comparison.” reads the post published by Rapid7. “The nature of the vulnerability means that unlike Log4Shell, it will be rare that an application uses the vulnerable component of Commons Text to process untrusted, potentially malicious input.”
Apache’s security team also confirmed that the issue is not comparable with Log4Shell.
“This issue is different from Log4Shell (CVE-2021-44228) because in Log4Shell, string interpolation was possible from the log message body, which commonly contains untrusted input. In the Apache Common Text issue, the relevant method is explicitly intended and clearly documented to perform string interpolation, so it is much less likely that applications would inadvertently pass in untrusted input without proper validation.” wrote the security team.
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