CVE-2015-1522 in Bro
Summary
by MITRE
analyzer/protocol/dnp3/DNP3.cc in Bro before 2.3.2 does not reject certain non-zero values of a packet length, which allows remote attackers to cause a denial of service (buffer overflow or buffer over-read) via a crafted DNP3 packet.
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Analysis
by VulDB Data Team • 12/02/2022
The vulnerability identified as CVE-2015-1522 resides within the DNP3 protocol analyzer component of Bro network security monitoring software version 2.3.1 and earlier. This flaw manifests in the analyzer/protocol/dnp3/DNP3.cc file where the software fails to properly validate packet length fields in DNP3 protocol communications. The DNP3 protocol serves as a critical communication standard for supervisory control and data acquisition systems, commonly deployed in industrial control systems and smart grid infrastructure. The vulnerability specifically affects the validation logic that processes packet length indicators, creating a scenario where non-zero values that should be rejected are instead accepted, leading to improper memory handling operations.
The technical implementation of this vulnerability stems from insufficient input validation within the DNP3 packet parsing routine. When a malformed DNP3 packet containing non-zero length values is processed, the analyzer attempts to allocate memory or access buffer regions based on these invalid length parameters. This processing behavior results in either buffer overflow conditions where data exceeds allocated memory boundaries or buffer over-read scenarios where the software attempts to access memory locations beyond the intended buffer limits. The flaw essentially creates a memory corruption condition that can be triggered through network-based attack vectors, as the DNP3 protocol analyzer processes incoming packets without adequate sanitization of length fields.
The operational impact of CVE-2015-1522 extends beyond simple denial of service, as it represents a fundamental security weakness in network monitoring infrastructure. Remote attackers capable of sending crafted DNP3 packets can exploit this vulnerability to disrupt network monitoring operations, potentially causing complete system crashes or unpredictable behavior in Bro instances monitoring DNP3 traffic. This vulnerability particularly affects industrial environments where Bro is deployed for security monitoring, as DNP3 protocol traffic is prevalent in critical infrastructure networks. The attack vector requires no authentication and can be executed over the network, making it particularly dangerous for operational technology environments where availability of monitoring systems is crucial for security operations. The vulnerability aligns with CWE-121, heap-based buffer overflow, and CWE-125, out-of-bounds read, representing core memory safety issues that can be leveraged for system compromise.
The mitigation strategy for CVE-2015-1522 involves upgrading to Bro version 2.3.2 or later, which includes fixed validation logic for DNP3 packet length fields. Network administrators should also implement network segmentation and access controls to limit exposure to potentially malicious DNP3 traffic, while monitoring for unusual packet patterns that might indicate exploitation attempts. Additionally, organizations should consider implementing intrusion detection systems with signature-based detection for DNP3 protocol anomalies, as outlined in the ATT&CK framework's network protocol analysis techniques. The vulnerability demonstrates the importance of proper input validation in protocol analyzers and highlights the need for comprehensive security testing of network monitoring tools in operational technology environments where system reliability and security are paramount.