CVE-2021-41157
Published: 26 October 2021
Summary
CVE-2021-41157 is a medium-severity Improper Authentication (CWE-287) vulnerability in Freeswitch Freeswitch. Its CVSS base score is 5.3 (Medium).
Operationally, ranked in the top 35.2% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-28267
Vulnerability details
FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. By default, SIP requests of the type SUBSCRIBE are not authenticated in the affected versions…
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of FreeSWITCH. Abuse of this security issue allows attackers to subscribe to user agent event notifications without the need to authenticate. This abuse poses privacy concerns and might lead to social engineering or similar attacks. For example, attackers may be able to monitor the status of target SIP extensions. Although this issue was fixed in version v1.10.6, installations upgraded to the fixed version of FreeSWITCH from an older version, may still be vulnerable if the configuration is not updated accordingly. Software upgrades do not update the configuration by default. SIP SUBSCRIBE messages should be authenticated by default so that FreeSWITCH administrators do not need to explicitly set the `auth-subscriptions` parameter. When following such a recommendation, a new parameter can be introduced to explicitly disable authentication.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Session content review can reveal authentication bypasses or failures in session establishment.
Assessments check authentication mechanisms for correct implementation and effectiveness, reducing successful authentication bypass attempts.
Documented IA policy and procedures require proper authentication mechanisms to be defined and followed, reducing improper authentication.
Requires adaptive authentication under specific conditions, directly strengthening authentication mechanisms against improper or insufficient authentication.
Identity providers centralize and enforce authentication mechanisms, reducing improper authentication.
Requires unique identification and authentication of organizational users, directly preventing improper authentication.
Enforces unique device identification and authentication before any connection is established, directly mitigating improper authentication weaknesses.
Directly requires implementation of compliant authentication mechanisms to cryptographic modules, preventing improper authentication.