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The vulnerability resides in the URN-based exemption logic of `@hulumi/policies` versions below 1.4.0. Pulumi assigns each resource a structured URN like hulumi:baseline:aws:SecureBucket$aws:s3/bucketV2:BucketV2::my-secure-bucket. The URN contains two key parts: the type chain (everything before the final ::) which includes parent component tokens separated by $, and the logical name (after ::) which is fully developer-controlled. Affected policy rules attempted to skip hardening checks for resources that belonged to a trusted parent component (e.g., SecureBucket) by searching for a substring such as `hulumi:baseline:aws:SecureBucket$` anywhere in the full URN string. Because the substring search is not anchored to the type-chain segment, an attacker can inject that exact trusted substring into the logical name portion. For example, naming a raw S3 bucket `hulumi:baseline:aws:SecureBucket$-evildb` would cause the substring match to succeed, making the policy believe the bucket is child of `SecureBucket` when it is actually a standalone, unhardened resource. This bypasses mandatory rules that enforce encryption, logging, or private ACLs. The anti-pattern was found in six different policy packs: AWS H4/H5, GitHub H1/H2, Cloudflare CF_DNS_1, Cloudflare CF_DNSSEC_1, and CIS v5 §2.1.1/§2.1.5. A developer or a compromised PR could exploit this to ship insecure resources that pass all policy checks, leading to data exposure or account takeover. The fix replaces substring matching with structured URN parsing that isolates the type chain segment and performs exact token matching against the trusted parent type, ignoring the logical name entirely.
DailyCVE Form:
Platform: @hulumi/policies npm
Version: Below 1.4.0
Vulnerability: Protection Mechanism Failure
Severity: High
date: Disclosed April 2025
Prediction: Patched in 1.4.0
What Undercode Say:
Simulate vulnerable substring check (DO NOT USE)
if [[ "$URN" == "hulumi:baseline:aws:SecureBucket$" ]]; then
echo "Skipping hardening (vulnerable)"
fi
Exploit by crafting logical name
pulumi up <<EOF
resource "bad_bucket" "aws:s3:Bucket" {
name = "hulumi:baseline:aws:SecureBucket$-pwned"
acl = "public-read" Would bypass rule
}
EOF
Verify vulnerable pattern in codebase
grep -rn 'strings\.Contains(urn, "hulumi:baseline:aws:SecureBucket$")' packages/policies/src/
Fixed helper usage (from 1.4.0)
node -e "const { isChildOfType } = require('@hulumi/policies/dist/urn'); console.log(isChildOfType(urn, 'hulumi:baseline:aws:SecureBucket'))"
Exploit:
Name any raw resource (S3 bucket, GitHub repo, Cloudflare zone) with a logical name containing the trusted parent substring (e.g., hulumi:baseline:aws:SecureBucket$-malicious). The vulnerable policy rule will treat it as a child of the hardened component and skip all mandatory checks (encryption, logging, private ACLs, DNSSEC). Commit the change; CI passes because all affected rules report compliance. Deploy the resource in its insecure state.
Protection:
Upgrade to `@hulumi/[email protected]` immediately. If upgrade is impossible, implement a custom lint rule that rejects any logical name containing the `$` character or the substring `:hulumi:baseline:` (though this may block legitimate names). Better, block PRs that use the vulnerable package version via dependency scanning. No reliable workaround exists because an attacker could encode the substring via Unicode or obfuscation.
Impact:
Consumers of `@hulumi/policies` could unknowingly deploy raw aws:s3:Bucket, github:Repository, cloudflare:Zone, and `cloudflare:DnsRecord` resources without required security defaults. This leads to public S3 buckets, unencrypted repositories, missing DNSSEC, and bypassed CIS benchmarks. All six policy packs were affected, making the exposure widespread across AWS, GitHub, and Cloudflare deployments.
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Sources:
Reported By: github.com
Extra Source Hub:
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