CAPEC-220
Client-Server Protocol Manipulation
An adversary takes advantage of weaknesses in the protocol by which a client and server are communicating to perform unexpected actions. Communication protocols are necessary to transfer messages between client and server applications. Moreover, different protocols may be used for different types of interactions.
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For example, an authentication protocol might be used to establish the identities of the server and client while a separate messaging protocol might be used to exchange data. If there is a weakness in a protocol used by the client and server, an attacker might take advantage of this to perform various types of attacks. For example, if the attacker is able to manipulate an authentication protocol, the attacker may be able spoof other clients or servers. If the attacker is able to manipulate a messaging protocol, the may be able to read sensitive information or modify message contents. This attack is often made easier by the fact that many clients and servers support multiple protocols to perform similar roles. For example, a server might support several different authentication protocols in order to support a wide range of clients, including legacy clients. Some of the older protocols may have vulnerabilities that allow an attacker to manipulate client-server interactions.
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Explain the attack pattern CAPEC-220: Client-Server Protocol Manipulation: how it unfolds, what it needs and how to prevent and detect it in my systems. Use https://capec.mitre.org/data/definitions/220.html and https://cve.bz/cve/capec/220?via=ask-ai-copy, which lists recent CVEs with the weaknesses it exploits. Cite the sources.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this attack pattern's id and public links.
Prerequisites
The client and/or server must utilize a protocol that has a weakness allowing manipulation of the interaction.
Resources required
The adversary must be able to identify the weakness in the utilized protocol and exploit it. This may require a sniffing tool as well as packet creation abilities. The adversary will be aided if they can force the client and/or server to utilize a specific protocol known to contain exploitable weaknesses.
Weaknesses it exploits
- CWE-757 Selection of Less-Secure Algorithm During Negotiation
Recent CVEs with these weaknesses
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In Modem, there is a possible information disclosure due to side channel information disclosure. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional exec…
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A remote user who can read encrypted objects in the S3 bucket can force a padding downgrade by altering the padding scheme recorded in an object's metadata to legacy PKCS#1 v1.5. Since this padding scheme is susceptible to the well-known B…
- 6.0CVE-2026-109952
The FreeRDP client 3.0.0 before 3.32.0 does not check a server-selected PROTOCOL_RDSTLS or PROTOCOL_HYBRID_EX against its enabled protocol set in nego_process_negotiation_response(), allowing a security protocol downgrade. A malicious serv…
- 8.8CVE-2026-107279
The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. In 3.0.12, a peer offering only Digest qop=auth-int causes mutual-authentication verification to be skipp…
- 8.7CVE-2026-107231
The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Prior to 3.0.13 and 2.16.1, Realm.Builder treats a Digest challenge that yields no usable nonce as a Basi…
- 9.2CVE-2026-102508
Improper Verification of Cryptographic Signature and Improper Certificate Validation in the OPC UA driver of Apache PLC4X (PLC4J) allows an attacker in a network position between client and server to impersonate the OPC UA server and to re…
- 8.7CVE-2026-89177
WeenyGenius, a computer lab management system by Howyar Technologies, has a Use of Insecure Protocol vulnerability. Due to the reliance on ZMTP Null mode, unauthenticated attackers on the same network can capture packets to leak transmitte…
The newest records naming one of them. Each weakness's page lists them all.
Related attack patterns
- Part of
- CAPEC-272 Protocol Manipulation
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