GHSA-CMR8-5W4C-44V8
Vulnerability from github – Published: 2022-09-20 20:45 – Updated: 2022-09-21 19:22Impact
Math.random and crypto.getRandomValues methods failed to use sufficiently random values. The initial value to seed the CSPRNG (cryptographically secure pseudorandom number generator) was baked-in to the final WebAssembly module meaning the sequence of numbers generated was predictable for that specific WebAssembly module. An attacker with access to that same WebAssembly module that calls the affected methods could use the fixed seed to predict random numbers generated by these functions. This information could be used to bypass cryptographic security controls, for example to disclose sensitive data encrypted by functions that use these generators.
Patches
The problem has been fixed in version 0.5.3.
Corrected Math.random and crypto.getRandomValues methods to always use sufficiently random values. The previous versions would use a CSPRNG (cryptographically secure pseudorandom number generator) which we would seed with a random value. However, due to our use of Wizer, the initial value to seed the CSPRNG was baked-in to the final WebAssembly module meaning the sequence of numbers generated was predictable for that specific WebAssembly module. The new implementations of both Math.random and crypto.getRandomValues do not use a CSPRNG and instead pull random values from WASI (WebAssembly System Interface) libc’s random_get function, which is always a sufficiently random value.
Workarounds
There are no workarounds, you must upgrade to version 0.5.3 or later.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "@fastly/js-compute"
},
"ranges": [
{
"events": [
{
"introduced": "0.4.0"
},
{
"fixed": "0.5.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2022-39218"
],
"database_specific": {
"cwe_ids": [
"CWE-330",
"CWE-335"
],
"github_reviewed": true,
"github_reviewed_at": "2022-09-20T20:45:10Z",
"nvd_published_at": "2022-09-20T20:15:00Z",
"severity": "HIGH"
},
"details": "### Impact\n\n`Math.random` and `crypto.getRandomValues` methods failed to use sufficiently random values. The initial value to seed the CSPRNG (cryptographically secure pseudorandom number generator) was baked-in to the final WebAssembly module meaning the sequence of numbers generated was predictable for that specific WebAssembly module. An attacker with access to that same WebAssembly module that calls the affected methods could use the fixed seed to predict random numbers generated by these functions. This information could be used to bypass cryptographic security controls, for example to disclose sensitive data encrypted by functions that use these generators.\n\n### Patches\n\nThe problem has been fixed in version 0.5.3.\n\nCorrected `Math.random` and `crypto.getRandomValues` methods to always use sufficiently random values. The previous versions would use a CSPRNG (cryptographically secure pseudorandom number generator) which we would seed with a random value. However, due to our use of Wizer, the initial value to seed the CSPRNG was baked-in to the final WebAssembly module meaning the sequence of numbers generated was predictable for that specific WebAssembly module. The new implementations of both Math.random and `crypto.getRandomValues` do not use a CSPRNG and instead pull random values from WASI (WebAssembly System Interface) libc\u2019s random_get function, which is always a sufficiently random value.\n\n### Workarounds\n\nThere are no workarounds, you must upgrade to version 0.5.3 or later.",
"id": "GHSA-cmr8-5w4c-44v8",
"modified": "2022-09-21T19:22:40Z",
"published": "2022-09-20T20:45:10Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/fastly/js-compute-runtime/security/advisories/GHSA-cmr8-5w4c-44v8"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-39218"
},
{
"type": "WEB",
"url": "https://github.com/fastly/js-compute-runtime/commit/65524ffc962644e9fc39f4b368a326b6253912a9"
},
{
"type": "PACKAGE",
"url": "https://github.com/fastly/js-compute-runtime"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Fastly Compute@Edge JS Runtime has fixed random number seed during compilation"
}
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.