apko allows users to build and publish OCI container images built from apk packages. From version 0.14.8 to before 1.1.0, expandapk.Split drains the first gzip stream of an APK archive via io.Copy(io.Discard, gzi) without explicit bounds. With an attacker-controlled input stream, this can force large gzip inflation work and lead to resource exhaustion (availability impact). The Split function reads the first tar header, then drains the remainder of the gzip stream by reading from the gzip reader directly without any maximum uncompressed byte limit or inflate-ratio cap. A caller that parses attacker-controlled APK streams may be forced to spend excessive CPU time inflating gzip data, leading to timeouts or process slowdown. This issue has been patched in version 1.1.0.
Weakness
The product does not properly control the allocation and maintenance of a limited resource.
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