[Bug 1879533] Re: busybox does not verify TLS connections with CONFIG_FEATURE_WGET_OPENSSL=y and CONFIG_FEATURE_WGET_HTTPS unset, and doesn't warn either about it

[Launchpad Bug Tracker]

This bug was fixed in the package busybox - 1:1.30.1-4ubuntu8

---------------
busybox (1:1.30.1-4ubuntu8) groovy; urgency=medium

  * Enable TLS verification with OpenSSL. LP: #1879533

busybox (1:1.30.1-4ubuntu7) groovy; urgency=medium

  * Enable TLS in initramfs flavour of wget applet, requires openssl. LP:
    #1879525

 -- Dimitri John Ledkov <xnox at ubuntu.com>  Wed, 20 May 2020 14:44:54
+0100

** Changed in: busybox (Ubuntu Groovy)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1879533

Title:
  busybox does not verify TLS connections with
  CONFIG_FEATURE_WGET_OPENSSL=y and CONFIG_FEATURE_WGET_HTTPS unset, and
  doesn't warn either about it

Status in busybox package in Ubuntu:
  Fix Released
Status in busybox source package in Focal:
  New
Status in busybox source package in Groovy:
  Fix Released

Bug description:
  [Impact]

   * CONFIG_FEATURE_WGET_OPENSSL=y enables https support in wget busybox
  applet using openssl

   * CONFIG_FEATURE_WGET_HTTPS=y enables https support in wget busybox
  applet using internal TLS code

   * CVE-2018-1000500 ensured that when CONFIG_FEATURE_WGET_HTTPS=y is
  used, a message is printed to notify the users that TLS verification
  is not perfomed.

   * However, when one configures with CONFIG_FEATURE_WGET_OPENSSL=y and
  CONFIG_FEATURE_WGET_HTTPS unset - no such message is printed.

   * Also TLS verification is not performed under OPENSSL case.

   * When performing https requests, it works openssl s_client and communicates with it to perform https download
   * Whilst doing so, it does not pass `-verify_return_error` option, meaning any verification errors are ignored

   * There is no warning that TLS verification was not performed

  [Test Case]

   * Preparation: sudo apt install busybox; or build busybox with
  CONFIG_FEATURE_WGET_OPENSSL=y

   * Test case: /bin/busybox wget https://untrusted-root.badssl.com/

   * Expected: download failed, or download suceeds with warning printed
  that verification is disabled

   * Observed: download success without a warning that verification is
  disabled.

  $ /bin/busybox wget https://untrusted-root.badssl.com/
  Connecting to untrusted-root.badssl.com (104.154.89.105:443)
  index.html           100% |*************************************************************************************|   600  0:00:00 ETA

  $ cat index.html  | grep certificate
    The certificate for this site is signed using an untrusted root.

  [Regression Potential]

   * The fact that /bin/busybox wget https:// succeeds without TLS
  verification might be relied upon. If this issue is fixed, ensure that
  `--no-check-certificate` is honored.

  [Other Info]

   * Proposed fix

     pass `-verify_return_error` to s_client, unless `--no-check-
  certificate` is specified

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