CVE-2017-11541 in macOS
Summary
by MITRE
tcpdump 4.9.0 has a heap-based buffer over-read in the lldp_print function in print-lldp.c, related to util-print.c.
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Analysis
by VulDB Data Team • 01/22/2021
The vulnerability CVE-2017-11541 represents a heap-based buffer over-read in tcpdump version 4.9.0 that occurs within the lldp_print function located in print-lldp.c and connected to util-print.c. This issue arises when tcpdump processes Link Layer Discovery Protocol packets, which are commonly used for network device discovery and information exchange. The flaw manifests during the parsing and display of LLDP frames, where the application fails to properly validate the length of incoming data before attempting to read beyond allocated buffer boundaries. The vulnerability is classified under CWE-125 as an out-of-bounds read, which can lead to unpredictable behavior and potential exploitation by malicious actors. This type of vulnerability falls within the ATT&CK technique T1059.007 for command and scripting interpreter, as it could enable attackers to execute arbitrary code through crafted network packets.
The technical implementation of this vulnerability stems from insufficient input validation within tcpdump's LLDP packet parsing logic. When processing LLDP frames, the lldp_print function does not adequately verify that the data length specified in the packet header matches the actual data available in the buffer. This mismatch allows an attacker to craft specially formatted LLDP packets that cause the application to read memory locations beyond the intended buffer boundaries. The heap-based nature of the over-read indicates that the vulnerability occurs in dynamically allocated memory regions, potentially exposing sensitive data from other heap allocations or causing application crashes. The root cause can be traced to improper bounds checking and lack of proper validation of packet structure elements, particularly those related to TLV (Type-Length-Value) fields commonly used in LLDP protocol implementations.
The operational impact of this vulnerability extends beyond simple application instability, as it creates potential attack vectors for network-based exploitation. An attacker positioned to intercept network traffic or manipulate LLDP packets could leverage this vulnerability to cause tcpdump to crash, potentially leading to denial of service conditions in network monitoring environments. In more severe scenarios, the over-read could expose sensitive information from adjacent memory locations, including authentication credentials, private keys, or other confidential data stored in the application's heap memory. The vulnerability is particularly concerning in environments where tcpdump is used for network security monitoring, as it could provide attackers with opportunities to gain insights into network topology or system configurations through information disclosure. The impact is amplified when considering that LLDP is widely deployed across enterprise networks for device discovery and network management purposes.
Mitigation strategies for CVE-2017-11541 should prioritize immediate patching of tcpdump installations to versions that address the buffer over-read vulnerability. Organizations should implement network segmentation and access controls to limit exposure to potentially malicious LLDP traffic, particularly in critical network segments where tcpdump is actively monitoring traffic. Network administrators should consider deploying intrusion detection systems that can identify and alert on suspicious LLDP packet patterns that may indicate exploitation attempts. Additionally, implementing proper input validation and bounds checking in network monitoring tools can help prevent similar vulnerabilities from occurring in other applications. Security teams should also conduct regular vulnerability assessments of network monitoring infrastructure to identify and remediate similar issues in other tools that process network protocol data. The vulnerability demonstrates the importance of thorough input validation in network protocol parsers and highlights the need for continuous security testing of network monitoring applications that handle untrusted data from network traffic.