CVE-2016-9569 in Carbon Black
Summary
by MITRE
The cbstream.sys driver in Carbon Black 5.1.1.60603 allows local users with admin privileges to cause a denial of service (out-of-bounds read and system crash) via a large counter value in an 0x62430028 IOCTL call.
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Analysis
by VulDB Data Team • 01/04/2020
The vulnerability identified as CVE-2016-9569 resides within the cbstream.sys kernel driver component of Carbon Black Endpoint Security software version 5.1.1.60603. This driver operates at the kernel level and serves as a critical interface for system monitoring and data streaming functionalities. The flaw manifests as an insufficient input validation mechanism that fails to properly sanitize user-supplied data before processing. When a malicious local administrator executes an IOCTL (Input/Output Control) operation with the specific command code 0x62430028, the driver does not adequately validate the counter parameter, leading to an out-of-bounds memory read condition. This particular vulnerability falls under the Common Weakness Enumeration category of CWE-129, which encompasses weaknesses related to insufficient validation of length of input buffers. The improper handling of the counter value allows an attacker to manipulate memory access patterns beyond the allocated buffer boundaries, resulting in unpredictable system behavior. The operational impact of this vulnerability is severe as it can be exploited by any local user with administrative privileges to trigger a system crash or complete denial of service condition. The out-of-bounds read operation can corrupt kernel memory structures, leading to system instability and potential complete system termination. This type of vulnerability is particularly dangerous in enterprise environments where administrative accounts are commonly present and may be compromised through various attack vectors. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1068, which involves the exploitation of local privileges to achieve system compromise. The vulnerability represents a classic example of a buffer overflow condition that occurs during kernel-level operations, where the lack of proper bounds checking creates an opportunity for privilege escalation and system instability. The security implications extend beyond simple denial of service as the system crash can potentially be leveraged to create conditions that allow for further exploitation or data corruption. Organizations utilizing Carbon Black software at this vulnerable version face significant risk exposure, particularly in environments where local administrative access is not strictly controlled or monitored. The vulnerability demonstrates the critical importance of proper input validation in kernel-mode drivers, as these components operate with the highest system privileges and can cause widespread disruption when compromised.
The technical exploitation of this vulnerability requires local administrative access, which significantly limits the attack surface but does not eliminate the risk entirely. The specific IOCTL command 0x62430028 represents a well-defined interface within the Carbon Black driver that accepts various parameters including counter values. When an attacker supplies an excessively large counter value, the driver's processing logic fails to validate the input against expected ranges or buffer boundaries. This validation failure results in the driver attempting to read memory locations that are outside the legitimate buffer allocation, causing memory corruption and system instability. The out-of-bounds read condition can manifest in various ways including page faults, memory corruption, or complete system crashes depending on the specific memory locations accessed. The vulnerability's impact is further amplified by the fact that it operates at the kernel level, meaning that any successful exploitation can lead to complete system compromise without requiring additional privilege escalation techniques. The flaw essentially creates a pathway for malicious code to execute arbitrary memory reads and potentially modify critical system structures, making it a serious concern for system administrators and security professionals. The vulnerability's classification as a denial of service condition reflects the primary impact, though the underlying memory corruption issues suggest potential for more sophisticated exploitation scenarios. The Carbon Black software ecosystem relies heavily on kernel drivers for real-time monitoring and data collection, making this vulnerability particularly concerning as it directly impacts the core functionality of the security solution.
Mitigation strategies for CVE-2016-9569 should focus on immediate software updates and administrative controls to reduce risk exposure. The most effective solution involves upgrading to a patched version of Carbon Black software that addresses the input validation flaw in the cbstream.sys driver. Organizations should implement strict access controls and privilege management to minimize the likelihood of unauthorized administrative access to systems running vulnerable software versions. Regular security assessments and vulnerability scanning should be conducted to identify systems running affected software versions and ensure timely patch deployment. The implementation of monitoring solutions that can detect unusual IOCTL activity patterns may provide additional defense-in-depth measures against exploitation attempts. Administrative users should be educated about the risks associated with local privilege escalation and the importance of maintaining strict access controls. System hardening practices including disabling unnecessary services and restricting local administrative privileges where possible can help reduce the attack surface. The vulnerability highlights the importance of proper input validation in kernel-mode components and serves as a reminder that security testing should include thorough analysis of driver interfaces and IOCTL handling routines. Organizations should also consider implementing network segmentation and monitoring to detect potential exploitation attempts and limit the lateral movement capabilities of attackers who might gain access to administrative accounts. Regular patch management processes should be established to ensure timely deployment of security updates and reduce the window of exposure for known vulnerabilities. The incident underscores the necessity of maintaining current security patches across all system components, particularly those operating at the kernel level where the potential for system compromise is highest.