CVE-2023-52081: Github.com/ewen lbh/ffcss Ewen-lbh/ffcss Late-Unicode Normalization Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-wpmx-564x-h2mh",
  "modified" : "2024-03-01T14:35:42Z",
  "published" : "2023-12-28T21:16:57Z",
  "aliases" : [ "CVE-2023-52081" ],
  "summary" : "ewen-lbh/ffcss Late-Unicode normalization vulnerability",
  "details" : "### Summary\nThe function `lookupPreprocess()` is meant to apply some transformations to a string by disabling characters in the regex `[-_ .]`. However, due to the use of late Unicode normalization of type NFKD, it is possible to bypass that validation and re-introduce all the characters in the regex `[-_ .]`. \n\n```go\n// lookupPreprocess applies transformations to s so that it can be compared\n// to search for something.\n// For example, it is used by (ThemeStore).Lookup\nfunc lookupPreprocess(s string) string {\n\treturn strings.ToLower(norm.NFKD.String(regexp.MustCompile(`[-_ .]`).ReplaceAllString(s, \"\")))\n}\n``` \n\nTake the following equivalent Unicode character U+2024 (․). Initially, the `lookupPreprocess()` function would compile the regex and replace the regular dot (.). However, the U+2024 (․) would bypass the `ReplaceAllString()`. When the normalization operation is applied to U+2024 (․), the resulting character will be U+002E (.). Thus, the dot was reintroduced back.\n\n### Impact\n\nThe `lookupPreprocess()` can be easily bypassed with equivalent Unicode characters like U+FE4D (﹍), which would result in the omitted U+005F (_), for instance. It should be noted here that the variable `s` is user-controlled data coming from [/cmd/ffcss/commands.go#L22-L28](https://github.com/ewen-lbh/ffcss/blob/master/cmd/ffcss/commands.go#L22-L28) the command args. The `lookupPreprocess()` function is only ever used to search for themes loosely (case insensitively, while ignoring dashes, underscores and dots), so the actual security impact is classified as low.\n\n### Remediation\n\nA simple fix would be to initially perform the Unicode normalization and then the rest of validations.\n\n### References\n\n - https://sim4n6.beehiiv.com/p/unicode-characters-bypass-security-checks\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/ewen-lbh/ffcss"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.2.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/ewen-lbh/ffcss/security/advisories/GHSA-wpmx-564x-h2mh"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-52081"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ewen-lbh/ffcss/commit/f9c491874b858a32fcae15045f169fd7d02f90dc"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/ewen-lbh/ffcss"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-176", "CWE-74" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-12-28T21:16:57Z",
    "nvd_published_at" : "2023-12-28T16:16:02Z"
  }
}