CVE-2024-42365
Published: 08 August 2024
Summary
CVE-2024-42365 is a high-severity Privilege Defined With Unsafe Actions (CWE-267) vulnerability in Asterisk Certified Asterisk. Its CVSS base score is 7.4 (High).
Operationally, ranked in the top 3.1% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
Deeper analysis
Asterisk, an open source PBX and telephony toolkit, contains an improper access control flaw in its Asterisk Manager Interface (AMI) that affects all versions prior to 18.24.2, 20.9.2, 21.4.2 and the corresponding certified-asterisk releases 18.9-cert11 and 20.7-cert2. An authenticated AMI user granted the originate write permission can leverage the CURL() dialplan function together with the SET application’s FILE() function to retrieve remote content and overwrite or append to any file under /etc/asterisk/, bypassing intended configuration restrictions.
An attacker with a low-privileged AMI account can therefore escalate privileges, inject arbitrary dialplan or module configuration, achieve remote code execution, or perform blind server-side request forgery against arbitrary protocols by writing chosen payloads into Asterisk configuration files that are subsequently loaded by the server.
The referenced commits and updated releases (18.24.2, 20.9.2, 21.4.2, 18.9-cert11, 20.7-cert2) contain the corrective changes that restrict the ability of originate-authorized AMI users to write arbitrary files via these functions. The EPSS score for this CVE rose from a low baseline to a peak of 0.4971, indicating that exploitation interest increased after public disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2024-39574
Vulnerability details
Asterisk is an open source private branch exchange (PBX) and telephony toolkit. Prior to asterisk versions 18.24.2, 20.9.2, and 21.4.2 and certified-asterisk versions 18.9-cert11 and 20.7-cert2, an AMI user with `write=originate` may change all configuration files in the `/etc/asterisk/` directory.…
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This occurs because they are able to curl remote files and write them to disk, but are also able to append to existing files using the `FILE` function inside the `SET` application. This issue may result in privilege escalation, remote code execution and/or blind server-side request forgery with arbitrary protocol. Asterisk versions 18.24.2, 20.9.2, and 21.4.2 and certified-asterisk versions 18.9-cert11 and 20.7-cert2 contain a fix for this issue.
- 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.
Use of granular security and privacy attributes enables finer access control than coarse permission models alone.
Documenting interface characteristics enables more granular control over internal access.
Requires the architecture to describe granularity and placement of controls, preventing insufficiently fine-grained access decisions.
Provides the necessary granularity by placing system management functions outside the reach of user-level access controls.
Isolation supplies an explicit, enforceable granularity boundary between security and non-security functions that coarser access-control schemes lack.