Horizon Alert
Summary of the vulnerability and why it matters
This advisory concerns a vulnerability in Apache Traffic Server, a web proxy and caching system. The issue allows an attacker to manipulate requests, potentially bypassing access controls, disrupting other users, or compromising cached information by exploiting how the server handles incomplete client requests.
- Attackers can bypass security controls and disrupt services.
- Crucial for protecting edge services and cached content.
- Verify relevance and exposure of this web traffic tool.
Attack Path
How an attacker could exploit the issue
An attacker can exploit this vulnerability by sending incomplete request bodies to Apache Traffic Server, specifically when using the "Expect: 100-continue" header. This causes the server to mishandle the connection, allowing the attacker to insert malicious requests that bypass security controls, disrupt other users, or corrupt cached data.
- Attackers can reach the vulnerable component over the network.
- Incomplete request bodies trigger the vulnerability.
- Risks include request smuggling and cache poisoning.
Live Threat
Current exploitation, exposure, and threat context
Apache Traffic Server, when improperly handling incomplete client request bodies, could allow an attacker to bypass access controls, disrupt service for other users, or poison the cache. This occurs when the server prematurely returns an origin connection to its pool while still expecting data from a client, leading to the next request on that connection being misinterpreted.
- Bypass access controls and poison cache.
- Attackers can manipulate incomplete requests.
- Disrupt service and compromise cache integrity.
Operational Fix
Recommended remediation, mitigation, and detection steps
Apache Traffic Server (ATS) administrators and platform owners are responsible for managing this critical vulnerability. The initial step is to locate all ATS deployments, determine their exposure to external networks, and assess their business criticality. This will inform prioritization for remediation, involving coordination with infrastructure, network, and security teams.
- Own the ATS inventory and exposure.
- Verify external reachability and criticality.
- Plan and execute remediation.
