Vulnerabilities
Misconfiguration
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CVE Vulnerabilities

CVE-2020-1927

URL Redirection to Untrusted Site ('Open Redirect')

Published: Apr 02, 2020 | Modified: Nov 21, 2024
CVSS 3.x
6.1
MEDIUM
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CVSS 2.x
5.8 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:N
RedHat/V2
RedHat/V3
6.1 MODERATE
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Ubuntu
LOW
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2020-1927
CWEhttps://cwe.mitre.org/data/definitions/601.html

In Apache HTTP Server 2.4.0 to 2.4.41, redirects configured with mod_rewrite that were intended to be self-referential might be fooled by encoded newlines and redirect instead to an an unexpected URL within the request URL.

Weakness

The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.

Affected Software

NameVendorStart VersionEnd Version
Http_serverApache2.4.0 (including)2.4.41 (including)
JBoss Core Services Apache HTTP Server 2.4.37 SP2RedHathttpd*
JBoss Core Services on RHEL 6RedHatjbcs-httpd24-apr-0:1.6.3-86.jbcs.el6*
JBoss Core Services on RHEL 6RedHatjbcs-httpd24-brotli-0:1.0.6-21.jbcs.el6*
JBoss Core Services on RHEL 6RedHatjbcs-httpd24-httpd-0:2.4.37-52.jbcs.el6*
JBoss Core Services on RHEL 6RedHatjbcs-httpd24-mod_cluster-native-0:1.3.12-41.Final_redhat_2.jbcs.el6*
JBoss Core Services on RHEL 6RedHatjbcs-httpd24-mod_http2-0:1.11.3-22.jbcs.el6*
JBoss Core Services on RHEL 6RedHatjbcs-httpd24-openssl-1:1.1.1c-16.jbcs.el6*
JBoss Core Services on RHEL 7RedHatjbcs-httpd24-apr-0:1.6.3-86.jbcs.el7*
JBoss Core Services on RHEL 7RedHatjbcs-httpd24-brotli-0:1.0.6-21.jbcs.el7*
JBoss Core Services on RHEL 7RedHatjbcs-httpd24-httpd-0:2.4.37-52.jbcs.el7*
JBoss Core Services on RHEL 7RedHatjbcs-httpd24-mod_cluster-native-0:1.3.12-41.Final_redhat_2.jbcs.el7*
JBoss Core Services on RHEL 7RedHatjbcs-httpd24-mod_http2-0:1.11.3-22.jbcs.el7*
JBoss Core Services on RHEL 7RedHatjbcs-httpd24-openssl-1:1.1.1c-16.jbcs.el7*
Red Hat Enterprise Linux 7RedHathttpd-0:2.4.6-95.el7*
Red Hat Enterprise Linux 8RedHathttpd:2.4-8030020200818000036.30b713e6*
Red Hat Software Collections for Red Hat Enterprise Linux 6RedHathttpd24-httpd-0:2.4.34-18.el6*
Red Hat Software Collections for Red Hat Enterprise Linux 7RedHathttpd24-httpd-0:2.4.34-18.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7RedHathttpd24-mod_md-1:2.0.8-1.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUSRedHathttpd24-httpd-0:2.4.34-18.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUSRedHathttpd24-mod_md-1:2.0.8-1.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSRedHathttpd24-httpd-0:2.4.34-18.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSRedHathttpd24-mod_md-1:2.0.8-1.el7*
Apache2Ubuntubionic*
Apache2Ubuntueoan*
Apache2Ubuntuesm-infra-legacy/trusty*
Apache2Ubuntuesm-infra/bionic*
Apache2Ubuntuesm-infra/focal*
Apache2Ubuntuesm-infra/xenial*
Apache2Ubuntufocal*
Apache2Ubuntutrusty*
Apache2Ubuntutrusty/esm*
Apache2Ubuntuupstream*
Apache2Ubuntuxenial*

Potential Mitigations

  • Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
  • When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
  • Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
  • Use a list of approved URLs or domains to be used for redirection.
  • When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
  • For example, ID 1 could map to “/login.asp” and ID 2 could map to “http://www.example.com/". Features such as the ESAPI AccessReferenceMap [REF-45] provide this capability.
  • Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
  • Many open redirect problems occur because the programmer assumed that certain inputs could not be modified, such as cookies and hidden form fields.

References

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