Horizon Alert
Summary of the vulnerability and why it matters
This critical vulnerability in the s3-proxy software could allow an unauthenticated attacker to bypass access controls. The issue stems from how the software interprets file paths differently during authentication and when accessing S3 buckets, potentially enabling unauthorized actions on sensitive data.
- Attackers can read, write, or delete data.
- The vulnerability is reachable from the internet.
- It impacts protected S3 namespaces.
Attack Path
How an attacker could exploit the issue
An attacker can exploit this vulnerability by sending specially crafted requests to the s3-proxy. The proxy's inconsistent handling of URL encoding and path interpretation allows attackers to bypass authentication checks. This bypass enables them to perform unauthorized actions like reading, writing, or deleting objects in protected S3 namespaces.
- Network access required.
- Target the proxy's authentication middleware.
- Manipulate URL encoding and path traversal.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability in oxyno-zeta/s3-proxy allows unauthenticated attackers to perform unauthorized read, write, or delete operations on S3 objects. The inconsistent interpretation of URL paths between authentication and the bucket handler, combined with specific glob patterns, enables attackers to bypass access controls. Given its nature as a proxy for S3, which is widely used for storing sensitive data, this vulnerability is attractive for attackers.
- Authentication bypass flaw.
- Affects network-accessible proxy.
- Public exploit code not yet observed.
Priority actions
Operational Fix
Recommended remediation, mitigation, and detection steps
Teams should prioritize identifying all instances of oxyno-zeta/s3-proxy and immediately upgrading to version 5.0.0 or later to address the authentication bypass vulnerability. If upgrading is not feasible, implement network-level controls to restrict access to the affected proxy and closely monitor traffic for any signs of unauthorized S3 operations.
- Upgrade s3-proxy to 5.0.0 or later.
- Restrict network access to the proxy.
- Monitor for unauthorized S3 object operations.
