CVE-2018-10858 in Samba
Summary
by MITRE
A heap-buffer overflow was found in the way samba clients processed extra long filename in a directory listing. A malicious samba server could use this flaw to cause arbitrary code execution on a samba client. Samba versions before 4.6.16, 4.7.9 and 4.8.4 are vulnerable.
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Analysis
by VulDB Data Team • 05/04/2023
The heap-buffer overflow vulnerability CVE-2018-10858 represents a critical security flaw in the Samba client implementation that specifically targets the processing of directory listings containing exceptionally long filenames. This vulnerability exists within the client-side handling of SMB protocol responses, where Samba clients attempt to parse and display directory entries from remote servers. The flaw manifests when a malicious Samba server crafts directory listings with filenames that exceed normal length constraints, triggering improper memory management during the parsing process. The vulnerability falls under CWE-121, heap-based buffer overflow, which occurs when a program writes more data to a buffer allocated on the heap than the buffer can accommodate, leading to memory corruption that can be exploited by attackers.
The technical exploitation of this vulnerability requires a malicious Samba server to send specially crafted directory listing responses containing oversized filename fields that cause the client's memory allocation routines to overflow the heap buffer. When the Samba client processes these malformed directory entries, the buffer overflow can overwrite adjacent memory locations, potentially corrupting program execution flow and allowing remote code execution. This type of attack aligns with ATT&CK technique T1059.007 for command and script injection, as successful exploitation could enable attackers to execute arbitrary code on vulnerable client systems. The vulnerability affects multiple Samba release lines, with versions prior to 4.6.16, 4.7.9, and 4.8.4 being susceptible, indicating the flaw was present across several major versions and had significant impact on the Samba ecosystem.
The operational impact of CVE-2018-10858 extends beyond simple denial of service scenarios, as it can enable complete system compromise when exploited successfully. Samba clients that process directory listings from untrusted servers become vulnerable attack vectors, particularly in environments where users might connect to malicious file servers or where network traffic can be intercepted and manipulated. The vulnerability is particularly concerning in enterprise environments where Samba clients are used to access shared resources, as attackers could leverage this flaw to establish persistent access to client systems. The exploitability of this vulnerability is enhanced by the fact that directory listing operations are common and often automated, making it difficult for users to avoid triggering the malicious behavior. Network administrators must consider that this vulnerability could be exploited in scenarios involving man-in-the-middle attacks or compromised servers within the network infrastructure.
Mitigation strategies for CVE-2018-10858 primarily focus on immediate software updates to patched Samba versions that contain proper buffer size validation and memory management fixes. Organizations should prioritize patching all affected Samba client installations across their network infrastructure, particularly those that connect to external or untrusted Samba servers. Additional protective measures include implementing network segmentation to limit access to Samba servers, enabling network monitoring to detect unusual directory listing patterns, and configuring Samba clients to operate in restricted modes that limit exposure to potentially malicious directory responses. The vulnerability highlights the importance of input validation and proper memory management in network protocol implementations, serving as a reminder of the critical need for security testing in client-side applications that process untrusted network data. System administrators should also consider implementing network access controls that restrict Samba client connectivity to trusted servers and monitor for anomalous directory listing behaviors that might indicate exploitation attempts.