CVE-2023-1428 in grpc
Summary
by MITRE • 06/09/2023
There exists an vulnerability causing an abort() to be called in gRPC. The following headers cause gRPC's C++ implementation to abort() when called via http2:
te: x (x != trailers)
:scheme: x (x != http, https)
grpclb_client_stats: x (x == anything)
On top of sending one of those headers, a later header must be sent that gets the total header size past 8KB. We recommend upgrading past git commit 2485fa94bd8a723e5c977d55a3ce10b301b437f8 or v1.53 and above.
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Analysis
by VulDB Data Team • 12/04/2024
The vulnerability described in CVE-2023-1428 represents a critical denial-of-service condition within the gRPC C++ implementation that can lead to abrupt process termination through the abort() system call. This flaw specifically affects the HTTP/2 handling mechanisms within gRPC's core networking stack, where certain header values trigger unexpected behavior that results in program termination. The vulnerability operates through a carefully crafted combination of HTTP/2 headers that, when processed together, cause the gRPC library to invoke abort() in its C++ implementation, effectively crashing any application that relies on this networking framework.
The technical exploitation mechanism involves three specific header conditions that individually do not cause immediate issues but become dangerous when combined with subsequent header processing. The te: x header where x is not equal to "trailers" triggers an internal validation failure, while the :scheme: x header where x is neither "http" nor "https" creates a similar validation error. Additionally, the grpclb_client_stats header with any value causes the same abort condition. These headers must be followed by additional headers that collectively exceed the 8KB total header size limit to trigger the actual abort condition, making this vulnerability particularly insidious as it requires careful header crafting and size manipulation to exploit successfully.
The operational impact of this vulnerability extends beyond simple service disruption, as it represents a potential attack vector that could be leveraged by malicious actors to cause widespread availability issues in systems relying on gRPC for microservices communication. Applications that do not properly validate or sanitize incoming HTTP/2 headers could become vulnerable to this attack, potentially affecting entire service architectures that depend on gRPC for inter-service communication. The vulnerability affects the fundamental networking layer of gRPC implementations, meaning that any application using gRPC C++ libraries could be at risk, particularly those deployed in high-traffic environments where header manipulation attacks might be more likely to occur.
This vulnerability aligns with CWE-248, which addresses "Uncaught Exception" conditions in software systems, and demonstrates how improper handling of HTTP/2 header validation can lead to program termination. From an ATT&CK framework perspective, this represents a denial-of-service technique that could be categorized under T1499.004 for network denial-of-service, potentially enabling broader attack chains that could disrupt service availability. The recommended mitigation strategy of upgrading past the specified git commit or version v1.53 and above addresses the root cause by implementing proper header validation and error handling mechanisms that prevent the abort() call from being triggered under malicious header conditions. Organizations should prioritize this upgrade across all systems using gRPC C++ implementations, particularly those exposed to untrusted network traffic or public-facing services that might be vulnerable to header-based attacks.