GHSA-6W7G-P4JH-RF92

Vulnerability from github – Published: 2021-12-20 18:24 – Updated: 2023-01-20 22:03
VLAI?
Summary
"Verify All" Returns Success Despite Validation Failures in Singularity
Details

Impact

The --all / -a option to singularity verify returns success even when some objects in a SIF container are not signed, or cannot be verified.

The SIF objects that are not verified are reported in WARNING log messages, but a Container Verified message and exit code of 0 are returned.

Workflows that verify a container using --all / -a and use the exit code as an indicator of success are vulnerable to running SIF containers that have unsigned, or modified, objects that may be exploited to introduce malicious behavior.

$ singularity verify -a image.sif 
WARNING: Missing signature for SIF descriptor 2 (JSON.Generic)
WARNING: Missing signature for SIF descriptor 3 (FS)
Container is signed by 1 key(s):

Verifying partition: Def.FILE:
12045C8C0B1004D058DE4BEDA20C27EE7FF7BA84
[LOCAL]   Unit Test <unit@test.com>
[OK]      Data integrity verified

INFO:    Container verified: image.sif

$ echo $?
0

Patches

Singularity 3.6.0 has a new implementation of sign/verify that fixes this issue.

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 --legacy-insecure flag for the singularity verify command, that will 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.

Workarounds

If you are unable to update to 3.6.0 ensure that you do not rely on the return code of singularity verify --all / -a as an indicator of trust in a container.

Note that other issues in the sign/verify implementation in Singularity < 3.6.0 allow additional means to introduce malicious behavior to a signed container.

For more information

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

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

See our Security Policy here: https://sylabs.io/security-policy

Severity ?
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/sylabs/singularity"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.5.0"
            },
            {
              "fixed": "3.6.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2020-13846"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": true,
    "github_reviewed_at": "2021-05-24T19:12:04Z",
    "nvd_published_at": "2020-07-14T18:15:00Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nThe `--all / -a` option to `singularity verify` returns success even when some objects in a SIF container are not signed, or cannot be verified.\n\nThe SIF objects that are not verified are reported in `WARNING` log messages, but a `Container Verified` message and exit code of `0`  are returned.\n\nWorkflows that verify a container using `--all / -a` and use the exit code as an indicator of success are vulnerable to running SIF containers that have unsigned, or modified, objects that may be exploited to introduce malicious behavior.\n\n```\n$ singularity verify -a image.sif \nWARNING: Missing signature for SIF descriptor 2 (JSON.Generic)\nWARNING: Missing signature for SIF descriptor 3 (FS)\nContainer is signed by 1 key(s):\n\nVerifying partition: Def.FILE:\n12045C8C0B1004D058DE4BEDA20C27EE7FF7BA84\n[LOCAL]   Unit Test \u003cunit@test.com\u003e\n[OK]      Data integrity verified\n\nINFO:    Container verified: image.sif\n\n$ echo $?\n0\n```\n\n\n### Patches\n\nSingularity 3.6.0 has a new implementation of sign/verify that fixes this issue.\n\nAll 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 \u003c 3.6.0 - e.g. Singularity 3.5.3 cannot verify containers signed by 3.6.0.\n\nVersion 3.6.0 includes a `--legacy-insecure` flag for the `singularity verify` command, that will 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.\n\n### Workarounds\n\nIf you are unable to update to 3.6.0 ensure that you do not rely on the return code of `singularity verify --all / -a` as an indicator of trust in a container.\n\nNote that other issues in the sign/verify implementation in Singularity \u003c 3.6.0 allow additional means to introduce malicious behavior to a signed container.\n\n\n### For more information\n\nGeneral questions about the impact of the advisory / changes made in the 3.6.0 release can be asked in the:\n\n* [Singularity Slack Channel](https://bit.ly/2m0g3lX)\n* [Singularity Mailing List](https://groups.google.com/a/lbl.gov/forum/??sdf%7Csort:date#!forum/singularity)\n\nAny sensitive security concerns should be directed to: security@sylabs.io\n\nSee our Security Policy here: https://sylabs.io/security-policy",
  "id": "GHSA-6w7g-p4jh-rf92",
  "modified": "2023-01-20T22:03:21Z",
  "published": "2021-12-20T18:24:43Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/hpcng/singularity/security/advisories/GHSA-6w7g-p4jh-rf92"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-13846"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sylabs/singularity"
    },
    {
      "type": "WEB",
      "url": "https://medium.com/sylabs"
    },
    {
      "type": "WEB",
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00046.html"
    },
    {
      "type": "WEB",
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00059.html"
    },
    {
      "type": "WEB",
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00053.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "\"Verify All\" Returns Success Despite Validation Failures in Singularity"
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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