id: GO-TEST-ID
modules:
    - module: github.com/sylabs/singularity
      versions:
        - introduced: 3.0.0+incompatible
          fixed: 3.6.0
summary: Execution Control List (ECL) Is Insecure in Singularity
description: |-
    ### Impact

    The Singularity Execution Control List (ECL) allows system administrators to set
    up a policy that defines rules about what signature(s) must be (or must not be)
    present on a SIF container image for it to be permitted to run.

    In Singularity 3.x versions below 3.6.0, the following issues allow the ECL to
    be bypassed by a malicious user:

    * Image integrity is not validated when an ECL policy is enforced.
    * The fingerprint required by the ECL is compared against the signature object
    descriptor(s) in the SIF file, rather than to a cryptographically validated
    signature. Thus, it is trivial to craft an arbitrary payload which will be
    permitted to run, even if the attacker does not have access to the private key
    associated with the fingerprint(s) configured in the ECL.

    ### Patches

    These issues are addressed in Singularity 3.6.0.

    All users are advised to upgrade to 3.6.0. Note that Singularity 3.6.0 uses a
    new signature format that is necessarily incompatible with Singularity < 3.6.0 -
    e.g. Singularity 3.5.3 cannot verify containers signed by 3.6.0.

    Version 3.6.0 includes a `legacyinsecure` option that can be set to
    `legacyinsecure = true` in `ecl.toml` to allow the ECL to perform verification
    of the older, and insecure, legacy signatures for compatibility with existing
    containers. This does not guarantee that containers have not been modified since
    signing, due to other issues in the legacy signature format. The option should
    be used only to temporarily ease the transition to containers signed with the
    new 3.6.0 signature format.

    ### Workarounds

    This issue affects any installation of Singularity configured to use the
    Execution Control List (ECL) functionality. There is no workaround if ECL is
    required.

    ### For more information

    General questions about the impact of the advisory / changes made in the 3.6.0
    release can be asked in the:

    * [Singularity Slack Channel](https://bit.ly/2m0g3lX)
    * [Singularity Mailing
    List](https://groups.google.com/a/lbl.gov/forum/??sdf%7Csort:date#!forum/singularity)

    Any sensitive security concerns should be directed to: security@sylabs.io

    See our Security Policy here: https://sylabs.io/security-policy
cves:
    - CVE-2020-13845
ghsas:
    - GHSA-pmfr-63c2-jr5c
references:
    - advisory: https://github.com/hpcng/singularity/security/advisories/GHSA-pmfr-63c2-jr5c
    - advisory: https://nvd.nist.gov/vuln/detail/CVE-2020-13845
    - web: https://medium.com/sylabs
    - web: http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00046.html
    - web: http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00059.html
    - web: http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00053.html
notes:
    - lint: 'github.com/sylabs/singularity: version 3.6.0 does not exist'
    - lint: references should contain at most one advisory link