CVE-2015-7852 in ntpd
Summary
by MITRE
ntpq in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (crash) via crafted mode 6 response packets.
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Analysis
by VulDB Data Team • 06/24/2022
The vulnerability identified as CVE-2015-7852 affects the ntpq utility within the Network Time Protocol implementation across multiple versions of the NTP software. This issue represents a significant security flaw that enables remote attackers to execute denial of service attacks against systems running affected NTP versions. The vulnerability specifically targets the mode 6 response packet handling mechanism within the ntpq utility, which is commonly used for querying time synchronization information from NTP servers.
The technical flaw stems from inadequate input validation and memory handling within the ntpq utility when processing mode 6 response packets. These packets are part of the standard NTP protocol communication mechanism used for client-server interactions and time synchronization queries. When maliciously crafted mode 6 packets are received by an affected system, the ntpq utility fails to properly validate the packet structure and contents, leading to memory corruption or buffer overflow conditions. This improper handling ultimately results in the crashing of the ntpq process and subsequent denial of service conditions that prevent legitimate time synchronization operations.
The operational impact of this vulnerability extends beyond simple service disruption as it can affect critical infrastructure components that rely on accurate time synchronization for their operations. Systems running affected NTP versions may experience complete loss of time synchronization capabilities, potentially leading to cascading failures in network services, logging systems, and security mechanisms that depend on synchronized timestamps. The remote nature of this attack means that adversaries can exploit the vulnerability from any location without requiring local access or authentication credentials, making it particularly dangerous in networked environments.
Organizations should prioritize immediate patching of all affected systems running NTP versions 4.2.x before 4.2.8p4 and 4.3.x before 4.3.77 to prevent exploitation. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation leading to memory corruption. From an attacker perspective, this vulnerability maps to ATT&CK technique T1499.004, which covers network denial of service attacks, and T1566.002, which involves spearphishing with social engineering. Additional mitigations include implementing network segmentation to limit exposure, configuring firewalls to restrict NTP traffic to trusted sources, and monitoring for unusual NTP packet patterns that may indicate exploitation attempts. The fix for this vulnerability involves proper input validation and memory management within the ntpq utility's packet processing routines to prevent malformed mode 6 packets from causing system crashes.