github - ghsa-498w-5j49-vqjg

GHSA-498W-5J49-VQJG

Vulnerability from github – Published: 2023-10-04 14:44 – Updated: 2023-10-13 23:13

Summary

gnark unsoundness in variable comparison / non-unique binary decomposition

Details

Impact

For some in-circuit values, it is possible to construct two valid decomposition to bits. In addition to the canonical decomposition of a, for small values there exists a second decomposition for a+r (where r is the modulus the values are being reduced by). The second decomposition was possible due to overflowing the field where the values are defined.

Internally, the comparison methods frontend.API.Cmp and frontend.API.IsLess used binary decomposition and checked the bitwise differences. This allows a malicious prover to construct a valid proof for a statement a < b even if a > b.

The issue impacts all users using API.Cmp or API.IsLess methods. Additionally, it impacts the users using bits.ToBinary or API.ToBinary methods if full-width decomposition is requested (the default behaviour if no options are given).

The issues does not impact comparison methods in field emulation (package std/math/emulated) and dedicated comparison package (std/math/cmp).

Patches

Fix has been implemented in pull request #835 and merged in commit 59a4087261a6c73f13e80d695c17b398c3d0934f to master branch. The release v0.9.0 and onwards include the fix.

The fix added additional comparison of the decomposed bit-vector to the modulus of the in-circuit values.

Workarounds

Upgrading to version v0.9.0 should fix the issue without needing to change the calls to value comparison methods.

Alternatively, users can use the std/math/cmp gadget, which additionally allows to bound the number of bits being compared, making the comparisons more efficient if the bound on the absolute difference of the values is known.

References

https://github.com/Consensys/gnark/pull/835
https://github.com/zkopru-network/zkopru/issues/116
https://github.com/iden3/circomlib/pull/48

Acknowledgement

The vulnerability was reported by Marcin Kostrzewa @ Reilabs.

Severity ?

5.5 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/consensys/gnark"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2023-44378"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-191",
      "CWE-697"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2023-10-04T14:44:08Z",
    "nvd_published_at": "2023-10-09T14:15:10Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nFor some in-circuit values, it is possible to construct two valid decomposition to bits. In addition to the canonical decomposition of `a`, for small values there exists a second decomposition for `a+r` (where `r` is the modulus the values are being reduced by). The second decomposition was possible due to overflowing the field where the values are defined.\n\nInternally, the comparison methods `frontend.API.Cmp` and `frontend.API.IsLess` used binary decomposition and checked the bitwise differences. This allows a malicious prover to construct a valid proof for a statement `a \u003c b` even if `a \u003e b`.\n\nThe issue impacts all users using `API.Cmp` or `API.IsLess` methods. Additionally, it impacts the users using `bits.ToBinary` or `API.ToBinary` methods if full-width decomposition is requested (the default behaviour if no options are given).\n\nThe issues does not impact comparison methods in field emulation (package `std/math/emulated`) and dedicated comparison package (`std/math/cmp`).\n\n### Patches\n\nFix has been implemented in pull request #835 and merged in commit 59a4087261a6c73f13e80d695c17b398c3d0934f to master branch. The release v0.9.0 and onwards include the fix.\n\nThe fix added additional comparison of the decomposed bit-vector to the modulus of the in-circuit values.  \n\n### Workarounds\n\nUpgrading to version v0.9.0 should fix the issue without needing to change the calls to value comparison methods.\n\nAlternatively, users can use the `std/math/cmp` gadget, which additionally allows to bound the number of bits being compared, making the comparisons more efficient if the bound on the absolute difference of the values is known.\n\n### References\n\n* https://github.com/Consensys/gnark/pull/835\n* https://github.com/zkopru-network/zkopru/issues/116\n* https://github.com/iden3/circomlib/pull/48\n\n### Acknowledgement\n\nThe vulnerability was reported by [Marcin Kostrzewa](https://github.com/kustosz) @ [Reilabs](https://reilabs.io/).",
  "id": "GHSA-498w-5j49-vqjg",
  "modified": "2023-10-13T23:13:57Z",
  "published": "2023-10-04T14:44:08Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Consensys/gnark/security/advisories/GHSA-498w-5j49-vqjg"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-44378"
    },
    {
      "type": "WEB",
      "url": "https://github.com/zkopru-network/zkopru/issues/116"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Consensys/gnark/pull/835"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Consensys/gnark/commit/59a4087261a6c73f13e80d695c17b398c3d0934f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Consensys/gnark"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-498w-5j49-vqjg"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "gnark unsoundness in variable comparison / non-unique binary decomposition"
}

CVE-2023-44378 (GCVE-0-2023-44378)

Vulnerability from cvelistv5 – Published: 2023-10-09 13:33 – Updated: 2024-09-19 13:52

Title

gnark vulnerable to unsoundness in variable comparison/non-unique binary decomposition

Summary

gnark is a zk-SNARK library that offers a high-level API to design circuits. Prior to version 0.9.0, for some in-circuit values, it is possible to construct two valid decomposition to bits. In addition to the canonical decomposition of `a`, for small values there exists a second decomposition for `a+r` (where `r` is the modulus the values are being reduced by). The second decomposition was possible due to overflowing the field where the values are defined. Upgrading to version 0.9.0 should fix the issue without needing to change the calls to value comparison methods.

Severity ?

7.1 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

CWE

CWE-191 - Integer Underflow (Wrap or Wraparound)
CWE-697 - Incorrect Comparison

Assigner

GitHub_M

References

URL

Tags

	https://github.com/Consensys/gnark/security/advis…	x_refsource_CONFIRM
	https://github.com/zkopru-network/zkopru/issues/116	x_refsource_MISC
	https://github.com/Consensys/gnark/commit/59a4087…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	Consensys	gnark	Affected: < 0.9.0

Show details on NVD website

JSON

To clipboard

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Sightings

Author	Source	Type	Date

Nomenclature

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.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
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.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-498W-5J49-VQJG

Impact

Patches

Workarounds

References

Acknowledgement

CVE-2023-44378 (GCVE-0-2023-44378)

Tags

Sightings

Nomenclature