CVE-2012-4502 in Chrony
Summary
by MITRE
Multiple integer overflows in pktlength.c in Chrony before 1.29 allow remote attackers to cause a denial of service (crash) via a crafted (1) REQ_SUBNETS_ACCESSED or (2) REQ_CLIENT_ACCESSES command request to the PKL_CommandLength function or crafted (3) RPY_SUBNETS_ACCESSED, (4) RPY_CLIENT_ACCESSES, (5) RPY_CLIENT_ACCESSES_BY_INDEX, or (6) RPY_MANUAL_LIST command reply to the PKL_ReplyLength function, which triggers an out-of-bounds read or buffer overflow. NOTE: versions 1.27 and 1.28 do not require authentication to exploit.
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Analysis
by VulDB Data Team • 01/10/2022
The vulnerability described in CVE-2012-4502 represents a critical security flaw in the Chrony time synchronization daemon version 1.28 and earlier, which is widely used for maintaining accurate system time across networked environments. This issue stems from improper input validation within the packet length handling functions of the software, specifically affecting the PKL_CommandLength and PKL_ReplyLength functions. The flaw enables remote attackers to manipulate the daemon's behavior through specially crafted network requests, potentially leading to system crashes and denial of service conditions that can severely impact time synchronization services across affected networks.
The technical implementation of this vulnerability involves integer overflow conditions that occur when processing network commands and replies related to client access control and subnet management. When the PKL_CommandLength function processes the REQ_SUBNETS_ACCESSED or REQ_CLIENT_ACCESSES commands, or when the PKL_ReplyLength function handles RPY_SUBNETS_ACCESSED, RPY_CLIENT_ACCESSES, RPY_CLIENT_ACCESSES_BY_INDEX, or RPY_MANUAL_LIST replies, the software fails to properly validate the length parameters. This failure results in integer overflows that can cause memory allocation errors leading to out-of-bounds memory reads or buffer overflow conditions. These conditions are classified under CWE-190 as integer overflow and under CWE-129 as insufficient bounds checking, representing fundamental flaws in input validation and memory management practices.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited remotely without requiring authentication in versions 1.27 and 1.28, making it particularly dangerous for networked environments where time synchronization services are critical. Attackers can leverage this flaw to crash the chronyd daemon, causing time synchronization to fail across multiple systems that depend on accurate timekeeping for security protocols, log analysis, and network operations. The vulnerability affects systems where chrony is used as a time server, potentially impacting critical infrastructure such as financial systems, network security appliances, and distributed computing environments where precise time synchronization is essential for proper operation and security enforcement.
The exploitation of this vulnerability aligns with ATT&CK technique T1499.001 for network denial of service attacks, and demonstrates how improper input validation can lead to system instability. Organizations using chrony should prioritize immediate patching to version 1.29 or later, which contains fixes addressing these integer overflow conditions. Additional mitigations include implementing network segmentation to restrict access to time synchronization services, deploying intrusion detection systems to monitor for suspicious command patterns, and establishing robust monitoring procedures for time synchronization service availability. The vulnerability highlights the importance of proper input validation and memory management in network services, particularly those handling untrusted network data, and serves as a reminder of the critical nature of time synchronization services in maintaining overall system security and operational integrity.