CVE-2018-19911 in FreeSWITCH
Summary
by MITRE
FreeSWITCH through 1.8.2, when mod_xml_rpc is enabled, allows remote attackers to execute arbitrary commands via the api/system or txtapi/system (or api/bg_system or txtapi/bg_system) query string on TCP port 8080, as demonstrated by an api/system?calc URI. This can also be exploited via CSRF. Alternatively, the default password of works for the freeswitch account can sometimes be used.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 04/18/2020
FreeSWITCH version 1.8.2 and earlier contains a critical remote command execution vulnerability that affects systems with mod_xml_rpc module enabled. This vulnerability exists in the API handling mechanisms that process system commands through specific URI endpoints on TCP port 8080. The flaw allows remote attackers to execute arbitrary system commands by crafting malicious query strings that target the api/system or txtapi/system endpoints, with alternative paths including api/bg_system and txtapi/bg_system. The vulnerability is particularly dangerous because it can be exploited through Cross-Site Request Forgery attacks, making it accessible via web-based attack vectors that do not require direct network access to the system.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the XML-RPC API processing module. When FreeSWITCH receives requests to the affected endpoints, it fails to properly validate or sanitize the command parameters passed through the query string, allowing malicious payloads to be interpreted and executed by the underlying operating system. The demonstration case using api/system?calc URI illustrates how simple system commands can be executed, potentially leading to complete system compromise. The vulnerability affects not only the core system commands but also allows attackers to leverage default credentials for the freeswitch account, which can be exploited when the default password "works" is left unchanged.
The operational impact of this vulnerability extends beyond simple remote code execution, as it provides attackers with full system access capabilities that can be leveraged for persistent access, data exfiltration, and further network infiltration. Attackers can use this vulnerability to escalate privileges, install backdoors, or deploy additional malware on compromised systems. The default password issue compounds the risk significantly, as many installations may not change the default credentials, making exploitation more likely. This vulnerability aligns with CWE-78 which describes improper neutralization of special elements used in OS commands, and represents a classic command injection attack vector that can be executed through web interfaces.
Organizations affected by this vulnerability should implement immediate mitigations including disabling the mod_xml_rpc module when not required, implementing strict firewall rules to restrict access to TCP port 8080, and changing default passwords for all administrative accounts. Network segmentation and monitoring of traffic to port 8080 should be implemented to detect potential exploitation attempts. The recommended approach includes applying the vendor-provided patches for FreeSWITCH versions 1.8.3 and later, which address the input validation issues in the XML-RPC API processing. Additionally, organizations should consider implementing web application firewalls to filter malicious requests and establish regular security audits to identify and remediate similar vulnerabilities in other components of their telephony infrastructure. This vulnerability demonstrates the critical importance of proper input validation and credential management in telephony systems that expose API interfaces to external networks.