group.of.nepali.translators team mailing list archive

[Marcus <1875299@xxxxxxxxxxxxxxxxxx>]

After configuring nginx and apache, the file index.php has to be placed
in the document root directory (/var/www/html). This PHP file outputs
the value of the variable $_SERVER['REMOTE_ADDR'] which should always
carry the client's real IP address and should always contain trustworthy
values when being processed by a webserver.

In order to keep this simple, the following IPv4 addresses will be used:

Server IP: 192.168.1.1
Client IP: 192.168.2.2

Now our client wants to access our site by using the following command:

curl http://192.168.1.1/index.php
Output: 192.168.2.2 (As expected, the real IP address of the requesting client)

Let's assume the client accesses a SEO friendly URL and should be
internally redirected to the file index.php. To test this, the following
curl command can be used:

curl http://192.168.1.1/seo-friendly-url/
Output: 192.168.2.2 (As expected)

So far so good. Let's assume our client provides the header X-Forwarded-
For with an arbitrary IP address:

curl http://192.168.1.1/seo-friendly-url/ -H "X-Forwarded-For: 1.1.1.1"
Output: 1.1.1.1 (Unexpected; should contain the real IP address instead of the Header value)


I hope the supplied configuration files and this short explanation can be of help. I am happy to provide additional information if needed.

** Also affects: apache2 (Debian)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1875299

Title:
  Apache's mod_remoteip: IP address spoofing via X-Forwarded-For when
  mod_rewrite rule is triggered

Status in apache2 package in Ubuntu:
  Confirmed
Status in apache2 source package in Xenial:
  Triaged
Status in apache2 package in Debian:
  New

Bug description:
  There is a bug in mod_remoteip (a part of Apache Web Server): https://bz.apache.org/bugzilla/show_bug.cgi?id=60251
  Although the status of this bug is "NEW", actually it was fixed in Apache 2.4.24.
  Although a CVE id was not requested yet, actually it is a vulnerability.

  The fix was not backported to Ubuntu 16.04 (xenial).

  Impact: if a victim uses Apache rewrite rules, then an attacker can
  spoof his IP address for logs and PHP scripts.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: apache2 2.4.18-2ubuntu3.14
  ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
  Uname: Linux 4.4.0-22-generic x86_64
  Apache2ConfdDirListing: False
  ApportVersion: 2.20.1-0ubuntu2.23
  Architecture: amd64
  Date: Mon Apr 27 13:17:43 2020
  SourcePackage: apache2
  UpgradeStatus: No upgrade log present (probably fresh install)
  error.log:
   
  modified.conffile..etc.apache2.apache2.conf: [modified]
  modified.conffile..etc.apache2.mods-available.dir.conf: [modified]
  modified.conffile..etc.apache2.mods-available.ssl.conf: [modified]
  modified.conffile..etc.apache2.ports.conf: [modified]
  modified.conffile..etc.apache2.sites-available.000-default.conf: [modified]
  modified.conffile..etc.apache2.sites-available.default-ssl.conf: [modified]
  mtime.conffile..etc.apache2.apache2.conf: 2020-04-23T15:45:48.416970
  mtime.conffile..etc.apache2.mods-available.dir.conf: 2020-04-23T12:03:13.711062
  mtime.conffile..etc.apache2.mods-available.ssl.conf: 2020-04-23T12:02:44.854484
  mtime.conffile..etc.apache2.ports.conf: 2020-04-23T15:45:48.169037
  mtime.conffile..etc.apache2.sites-available.000-default.conf: 2020-04-23T15:45:48.197030
  mtime.conffile..etc.apache2.sites-available.default-ssl.conf: 2020-04-23T15:45:48.225022

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