CVE-2020-8284
Description
A malicious server can use the PASV response to trick curl into connecting back to a given IP address and port, and this way potentially make curl extract information about services that are otherwise private and not disclosed, for example doing port scanning and service banner extractions. If curl operates on a URL provided by a user, a user can exploit that and pass in a URL to a malicious FTP server instance without needing any server breach to perform the attack.
Mitigation
This flaw can be mitigated in curl as shipped with Red Hat Enterprise Linux and Red Hat Software Collections when using curl by passing the `--ftp-skip-pasv-ip` command line option to curl. For usage of libcurl, set `CURLOPT_FTP_SKIP_PASV_IP` to `1L`[1]. Note that these mitigations could cause problems in the uncommon instance that the server needs the client to connect back to an IP other than the control connection IP address.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 3.1 | 3.7 | 3.7 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | High | High |
| Privileges Required | Low | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | Low | Low | Low |
| Integrity Impact | None | None | None |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data
Acknowledgements
Red Hat would like to thank Varnavas Papaioannou for reporting this issue.
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