CVE-2017-18349 Scanner

Fastjson is a high-performance JSON parser library in Java used by developers to handle JSON data swiftly in web applications and systems. It finds use in various applications that require parsing JSON data quickly due to its efficient performance and feature-rich capabilities. Initially developed by Alibaba, it is incorporated into numerous software projects to enhance data handling capabilities. However, this library's extensive functionality must be carefully managed, as improper configurations can lead to security vulnerabilities. Despite its broad adoption, developers must remain cautious of potential security implications stemming from using out-of-date versions of the library. Overall, Fastjson facilitates managing JSON data across diverse Java applications but warrants careful attention to security configuration and updates.

Remote Code Execution (RCE) vulnerabilities allow attackers to run arbitrary code on targeted systems. In the context of Fastjson, improperly parsing certain JSON inputs can lead to code execution vulnerabilities. Specifically, the vulnerability arises when a crafted JSON request is processed, enabling the attacker to execute arbitrary payloads. This vulnerability affects versions of Fastjson before 1.2.25 and potentially other software leveraging vulnerable Fastjson implementations. With remote code execution being a significant threat, it is crucial for systems to secure endpoints processing JSON data. Therefore, ensuring robust input validation and updating to secured library versions is vital to mitigate such vulnerabilities.

In technical terms, the vulnerability in Fastjson pertains to insecure deserialization of JSON data leading to RCE. The vulnerable endpoint in systems utilizing this library typically involves JSON processing routes such as `/json`, while the dangerous parameter often includes the `dataSourceName` with a malicious payload. Exploitation involves crafting requests that coerce the Fastjson parser to instantiate dangerous classes or execute unexpected methods. Attackers may craft payloads using `rmi://` URIs to initiate unauthorized remote method invocations. Ensuring security in JSON parsing by disabling auto-type functionality and employing strict input validation can mitigate these risks. Staying informed about how deserialization occurs in application environments is crucial.

If exploited, this RCE vulnerability can lead to severe consequences on the compromised system. Attackers may gain control to execute arbitrary commands, potentially causing data breaches or facilitating further exploits. Persistent backdoors can be embedded, posing long-term security threats. Sensitive data could be extracted or altered, and operational disruptions are possible if system components are manipulated. Consequently, the risk of losing confidential information or system control underpins significant reputational and financial damage. Consequently, timely updates and robust security validations are imperative to protect systems against such vulnerabilities.

REFERENCES

• https://nvd.nist.gov/vuln/detail/CVE-2017-18349
• https://github.com/alibaba/fastjson/wiki/security_update_20170315
• https://github.com/pippo-java/pippo/issues/466
• https://github.com/h0cksr/Fastjson--CVE-2017-18349-
• https://fortiguard.com/encyclopedia/ips/44059
• https://www.exploit-db.com/exploits/45983