Executive Summary
Summary | |
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Title | HTTP Request Smuggling in Web Proxies |
Informations | |||
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Name | VU#357312 | First vendor Publication | 2021-08-06 |
Vendor | VU-CERT | Last vendor Modification | 2021-08-12 |
Severity (Vendor) | N/A | Revision | M |
Security-Database Scoring CVSS v3
Cvss vector : N/A | |||
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Overall CVSS Score | NA | ||
Base Score | NA | Environmental Score | NA |
impact SubScore | NA | Temporal Score | NA |
Exploitabality Sub Score | NA | ||
Calculate full CVSS 3.0 Vectors scores |
Security-Database Scoring CVSS v2
Cvss vector : | |||
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Cvss Base Score | N/A | Attack Range | N/A |
Cvss Impact Score | N/A | Attack Complexity | N/A |
Cvss Expoit Score | N/A | Authentication | N/A |
Calculate full CVSS 2.0 Vectors scores |
Detail
OverviewHTTP web proxies and web accelerators that support HTTP/2 for an HTTP/1.1 backend webserver are vulnerable to HTTP Request Smuggling. DescriptionThe affected systems allow invalid characters such as carriage return and newline characters in HTTP/2 headers. When an attacker passes these invalid contents to a vulnerable system, the forwarded HTTP/1 request includes the unintended malicious data. This is commonly known as HTTP Request Splitting. In the case of HTTP web proxies, this vulnerability can lead to HTTP Request smuggling, which enables an attacker to access protected internal sites. ImpactAn attacker can send a crafted HTTP/2 request with malicious content to bypass network security measures, thereby reaching internal protected servers and accessing sensitive data. SolutionApply updatesInstall vendor-provided patches and updates to ensure malicious HTTP/2 content is blocked or rejected as described in RFC 7540 (Section 8.1.2.6) and RFC 7540 (Section 10.3). Both "request" and "response" should be inspected by the web proxy and rejected in accordance with Stream Error Handling as described in RFC 7450 (Section 5.4.2). Inspect and block anomalous HTTP/2 trafficIf HTTP/2 is not supported, block the protocol on the web proxies to avoid abuse of HTTP/2 protocol. Where HTTP/2 is supported, enforce strict rules for HTTP header checks to ensure malicious headers are normalized or rejected. Test and verify your web proxyScan your public web server proxy with OWASP recommended tests to ensure your web servers are not vulnerable to abuse via HTTP response splitting. AcknowledgementsThanks to the reporter James Kettle of PortSwigger for the information about this vulnerability. This document was written by Timur Snoke. |
Original Source
Url : https://kb.cert.org/vuls/id/357312 |
Alert History
Date | Informations |
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2021-09-23 17:17:41 |
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2021-08-12 17:17:41 |
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2021-08-09 17:17:38 |
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2021-08-06 17:17:38 |
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