ghsa-72qw-p7hh-m3ff
Vulnerability from github
Published
2023-10-19 12:33
Modified
2023-10-19 12:33
Severity ?
4.6 (Medium) - CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
TorBot vulnerable to Inefficient Regular Expression Complexity in validate_link
Details

Summary

The torbot.modules.validators.validate_link function uses the python-validators URL validation regex. This particular regular expression has an exponential complexity which allows an attacker to cause an application crash using a well-crafted argument..

Details

https://github.com/DedSecInside/TorBot/blob/d2b89192379ad033ffc7044efff26e16ccc02d5a/torbot/modules/validators.py#L13

An attacker can use a well-crafted URL argument to exploit the vulnerability in the regular expression and cause a Denial of Service on the system.

PoC

I have uploaded a secret gist containing a PoC (https://gist.github.com/ikkebr/6041055314f1cfb8e65b2a1acbaae12c). By adding one special character at the end of the user argument of the URL, the regular expression will take exponentially longer to compute.

For a string of size 10k, the regex will take 0.01s without the well-crafted URL and 1.3s with the well-crafted URL exploit. For a string of size 50k, the regex will take 0.03s without the well-crafted URL and 35s with the well-crafted URL exploit. For a string of size 100k, the regex will take 0.05s without the well-crafted URL and over 200s with the well-crafted URL exploit.

The regular expression used in the validators library versions [0.20, 0.11] is vulnerable to this attack. Version 0.21 appears to be unaffected, but it no longer contains a single regular expression.

Impact

An attacker could exploit this vulnerability to cause a denial of service or increased resource usage.

Show details on source website

To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "torbot"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2023-45813"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1333"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2023-10-19T12:33:03Z",
    "nvd_published_at": "2023-10-18T21:15:09Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n_The torbot.modules.validators.validate_link function uses the python-validators URL validation regex. This particular regular expression has an exponential complexity which allows an attacker to cause an application crash using a well-crafted argument.._\n\n### Details\nhttps://github.com/DedSecInside/TorBot/blob/d2b89192379ad033ffc7044efff26e16ccc02d5a/torbot/modules/validators.py#L13\n\nAn attacker can use a well-crafted URL argument to exploit the vulnerability in the regular expression and cause a Denial of Service on the system.\n\n### PoC\nI have uploaded a secret gist containing a PoC (https://gist.github.com/ikkebr/6041055314f1cfb8e65b2a1acbaae12c). By adding one special character at the end of the user argument of the URL, the regular expression will take exponentially longer to compute.\n\nFor a string of size 10k, the regex will take 0.01s without the well-crafted URL and 1.3s with the well-crafted URL exploit.\nFor a string of size 50k, the regex will take 0.03s without the well-crafted URL and 35s with the well-crafted URL exploit.\nFor a string of size 100k, the regex will take 0.05s without the well-crafted URL and over 200s with the well-crafted URL exploit.\n\nThe regular expression used in the validators library versions [0.20, 0.11] is vulnerable to this attack. Version 0.21 appears to be unaffected, but it no longer contains a single regular expression.\n\n### Impact\nAn attacker could exploit this vulnerability to cause a denial of service or increased resource usage.\n",
  "id": "GHSA-72qw-p7hh-m3ff",
  "modified": "2023-10-19T12:33:03Z",
  "published": "2023-10-19T12:33:03Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/DedSecInside/TorBot/security/advisories/GHSA-72qw-p7hh-m3ff"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-45813"
    },
    {
      "type": "WEB",
      "url": "https://github.com/DedSecInside/TorBot/commit/ef6e06bc7785355b1701d5524eb4550441086ac4"
    },
    {
      "type": "WEB",
      "url": "https://gist.github.com/ikkebr/6041055314f1cfb8e65b2a1acbaae12c"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/DedSecInside/TorBot"
    },
    {
      "type": "WEB",
      "url": "https://github.com/DedSecInside/TorBot/blob/d2b89192379ad033ffc7044efff26e16ccc02d5a/torbot/modules/validators.py#L13"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "TorBot vulnerable to Inefficient Regular Expression Complexity in validate_link"
}


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