ocaml.lang.security.hashtable-dos.ocamllint-hashtable-dos

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Creating a Hashtbl without the optional random number parameter makes it prone to DoS attacks when attackers are able to fill the table with malicious content. Hashtbl.randomize or the R flag in the OCAMLRUNPARAM are other ways to randomize it.

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Defintion

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rules:
  - id: ocamllint-hashtable-dos
    patterns:
      - pattern: Hashtbl.create $Y
      - pattern-not: Hashtbl.create $Y ~random:true
    message: Creating a Hashtbl without the optional random number parameter makes
      it prone to DoS attacks when attackers are able to fill the table with
      malicious content. Hashtbl.randomize or the R flag in the OCAMLRUNPARAM
      are other ways to randomize it.
    languages:
      - ocaml
    severity: WARNING
    metadata:
      category: security
      references:
        - https://v2.ocaml.org/api/Hashtbl.html
      technology:
        - ocaml
      cwe: "CWE-399: Resource Management Errors (4.12)"
      confidence: LOW
      likelihood: LOW
      impact: LOW
      subcategory:
        - audit
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]
      vulnerability_class:
        - Other

Examples

hashtable-dos.ml

(* ruleid:ocamllint-hashtable-dos *)
let h = Hashtbl.create 16 in
for i = 1 to 1000 do Hashtbl.add h i (i * 2) done;
Printf.printf "%i elements\n" (Hashtbl.length h);

let j = Hashtbl.create 16 ~random:true in
for i = 1 to 1000 do Hashtbl.add j i (i * 2) done;
Printf.printf "%i elements\n" (Hashtbl.length j);