CVE-2020-7610 in bson
Summary
by MITRE
All versions of bson before 1.1.4 are vulnerable to Deserialization of Untrusted Data. The package will ignore an unknown value for an object's _bsotype, leading to cases where an object is serialized as a document rather than the intended BSON type.
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Analysis
by VulDB Data Team • 05/12/2024
The vulnerability identified as CVE-2020-7610 affects all versions of the bson package prior to 1.1.4 and represents a critical deserialization flaw that falls under the CWE-502 category of Deserialization of Untrusted Data. This vulnerability occurs when the bson library encounters an unknown value for an object's _bsotype field during the deserialization process, causing the system to improperly handle object type information and serialize objects as documents rather than their intended BSON types. The issue stems from insufficient validation of the _bsotype field, which serves as a type identifier within the BSON serialization format used by MongoDB and other systems.
The technical flaw manifests when malicious actors craft specially crafted BSON data containing unexpected _bsotype values that bypass normal validation checks. This allows attackers to manipulate the deserialization process and potentially execute arbitrary code or cause unexpected behavior within applications that rely on the bson library for data processing. The vulnerability is particularly dangerous because it operates at the core serialization layer where data integrity and type safety are paramount. When the library encounters an unknown _bsotype value, it defaults to treating the object as a document type rather than attempting to validate or reject the malformed input, creating a pathway for attackers to exploit the type confusion behavior.
The operational impact of CVE-2020-7610 extends across numerous applications and systems that utilize the bson library for data serialization and deserialization tasks. Applications using MongoDB drivers, Node.js environments, and any system relying on BSON format for data interchange become vulnerable to remote code execution or data manipulation attacks. This vulnerability directly aligns with ATT&CK technique T1210 which involves exploiting weaknesses in remote services to gain unauthorized access. The attack surface is particularly wide given that bson is a foundational library used by many popular frameworks and databases, making it a prime target for attackers seeking to compromise server-side applications that process untrusted data inputs.
Mitigation strategies for CVE-2020-7610 require immediate patching of affected bson library versions to 1.1.4 or later, where the library properly validates _bsotype values and rejects unknown or malformed type identifiers. Organizations should implement comprehensive input validation at multiple layers, including application-level checks that verify BSON data integrity before processing. Network segmentation and access controls should be strengthened to limit exposure of systems that handle untrusted BSON data. Additionally, monitoring systems should be configured to detect anomalous deserialization patterns or unexpected _bsotype values that could indicate exploitation attempts. The fix implemented in version 1.1.4 addresses the core issue by introducing proper validation mechanisms that ensure only recognized BSON types are processed, preventing the type confusion that enabled the vulnerability. Organizations should also conduct thorough vulnerability assessments to identify all systems using affected bson versions and implement proper security testing procedures to verify the effectiveness of the applied patches.