The brace-expansion library generates arbitrary strings containing a common prefix and suffix. Prior to versions 5.0.5, 3.0.2, 2.0.3, and 1.1.13, a brace pattern with a zero step value (e.g., {1..2..0}) causes the sequence generation loop to run indefinitely, making the process hang for seconds and allocate heaps of memory. Versions 5.0.5, 3.0.2, 2.0.3, and 1.1.13 fix the issue. As a workaround, sanitize strings passed to expand() to ensure a step value of 0 is not used.
Weakness
The product does not properly control the allocation and maintenance of a limited resource.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Brace-expansion | Juliangruber | * | 1.1.13 (excluding) |
| Brace-expansion | Juliangruber | 2.0.0 (including) | 2.0.3 (excluding) |
| Brace-expansion | Juliangruber | 3.0.0 (including) | 3.0.2 (excluding) |
| Brace-expansion | Juliangruber | 5.0.0 (including) | 5.0.5 (excluding) |
| Node-brace-expansion | Ubuntu | upstream | * |
Potential Mitigations
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/147.html
- https://cwe.mitre.org/data/definitions/227.html
- https://cwe.mitre.org/data/definitions/492.html
References
- https://github.com/juliangruber/brace-expansion/blob/daa71bcb4a30a2df9bcb7f7b8daaf2ab30e5794a/src/index.ts#L107-L113
- https://github.com/juliangruber/brace-expansion/blob/daa71bcb4a30a2df9bcb7f7b8daaf2ab30e5794a/src/index.ts#L184
- https://github.com/juliangruber/brace-expansion/commit/311ac0d54994158c0a384e286a7d6cbb17ee8ed5
- https://github.com/juliangruber/brace-expansion/commit/7fd684f89fdde3549563d0a6522226a9189472a2
- https://github.com/juliangruber/brace-expansion/commit/b9cacd9e55e7a1fa588fe4b7bb1159d52f1d902a
- https://github.com/juliangruber/brace-expansion/issues/98
- https://github.com/juliangruber/brace-expansion/pull/95
- https://github.com/juliangruber/brace-expansion/pull/96
- https://github.com/juliangruber/brace-expansion/pull/97
- https://github.com/juliangruber/brace-expansion/security/advisories/GHSA-f886-m6hf-6m8v