CVE-2012-4503 in Chrony
Summary
by MITRE
cmdmon.c in Chrony before 1.29 allows remote attackers to obtain potentially sensitive information from stack memory via vectors related to (1) an invalid subnet in a RPY_SUBNETS_ACCESSED command to the handle_subnets_accessed function or (2) a RPY_CLIENT_ACCESSES command to the handle_client_accesses function when client logging is disabled, which causes uninitialized data to be included in a reply.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 01/10/2022
The vulnerability described in CVE-2012-4503 resides within the chrony time synchronization daemon version 1.28 and earlier, specifically in the cmdmon.c component that handles command monitoring functionality. This flaw represents a classic information disclosure vulnerability that occurs when the system fails to properly initialize memory before including it in response payloads. The issue manifests in two distinct scenarios involving different command handling functions within the chrony daemon's network interface. The first scenario involves improper handling of invalid subnet data within the RPY_SUBNETS_ACCESSED command, while the second involves the RPY_CLIENT_ACCESSES command when client logging functionality is disabled. Both situations result in the daemon inadvertently exposing uninitialized stack memory contents to remote attackers through network responses.
The technical root cause of this vulnerability stems from inadequate memory initialization practices within the command handling functions. When the handle_subnets_accessed function processes an invalid subnet in the RPY_SUBNETS_ACCESSED command, or when handle_client_accesses processes the RPY_CLIENT_ACCESSES command with client logging disabled, the system fails to properly zero out or initialize memory buffers before populating them with data for network transmission. This memory corruption leads to the inclusion of arbitrary stack contents in the response packets, potentially exposing sensitive information such as cryptographic keys, session tokens, or other confidential data that may have previously resided in the memory locations. The vulnerability is classified as a memory exposure issue that aligns with CWE-248, which addresses "Uncaught Exception" and related memory handling flaws, and represents a specific case of information exposure through uninitialized memory access.
From an operational impact perspective, this vulnerability creates significant security implications for systems relying on chrony for time synchronization services. Remote attackers can exploit this flaw to potentially extract sensitive information from the memory space of the chrony daemon, which could lead to credential compromise, session hijacking, or the exposure of system-specific data that might aid in further attacks. The attack vector is particularly concerning as it requires no authentication and can be executed over the network, making it accessible to any external party with network connectivity to the affected system. The vulnerability directly impacts the confidentiality aspect of the CIA triad and can be classified under ATT&CK technique T1005 for "Data from Local System" and T1041 for "Exfiltration Over C2 Channel" when combined with other exploitation techniques.
The recommended mitigation strategy involves upgrading to chrony version 1.29 or later, which contains the necessary patches to properly initialize memory buffers before including them in network responses. System administrators should also implement network segmentation and access controls to limit exposure of the chrony service to trusted networks only, while monitoring for unusual network traffic patterns that might indicate exploitation attempts. Additionally, regular security assessments and vulnerability scanning should be conducted to identify and remediate similar memory handling issues in other network services. Organizations should consider implementing intrusion detection systems that can identify anomalous responses containing unexpected data patterns that might indicate exploitation of this or similar information disclosure vulnerabilities. The patch addresses the fundamental memory initialization flaw and ensures that network responses contain only properly validated and initialized data, preventing the accidental exposure of stack contents to unauthorized parties.