CVE-2014-7913 in Android
Summary
by MITRE
The print_option function in dhcp-common.c in dhcpcd through 6.9.1, as used in dhcp.c in dhcpcd 5.x in Android before 5.1 and other products, misinterprets the return value of the snprintf function, which allows remote DHCP servers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted message.
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Analysis
by VulDB Data Team • 06/07/2022
The vulnerability identified as CVE-2014-7913 represents a critical buffer overflow condition within the dhcpcd DHCP client implementation that affects multiple versions including dhcpcd 5.x in Android systems prior to version 5.1. This flaw exists in the print_option function located within dhcp-common.c, where the software incorrectly handles the return value from the snprintf system call. The improper interpretation of snprintf's return value creates a scenario where memory corruption can occur, potentially leading to arbitrary code execution or denial of service conditions. The vulnerability specifically impacts systems that process DHCP messages from untrusted network sources, making it particularly dangerous in networked environments where DHCP servers may be compromised or malicious.
The technical root cause of this vulnerability stems from a classic buffer management error where the return value of snprintf is not properly validated before being used for subsequent operations. When snprintf processes a formatted string, it returns the number of characters that would have been written if the buffer was sufficiently large, rather than the number of characters actually written. The dhcpcd implementation incorrectly assumes that snprintf will always write to the buffer, leading to potential out-of-bounds memory access when the return value exceeds the allocated buffer size. This type of error maps directly to CWE-121, which addresses buffer overflow conditions in stack-based buffers, and CWE-122, which covers heap-based buffer overflows. The vulnerability demonstrates a clear violation of secure coding practices where input validation and return value checking are insufficiently implemented.
The operational impact of CVE-2014-7913 extends beyond simple denial of service to encompass potential remote code execution capabilities that could be exploited by malicious DHCP servers on the network. An attacker positioned to control or influence DHCP traffic can craft specifically formatted DHCP option messages that trigger the buffer overflow condition when processed by vulnerable dhcpcd implementations. This attack vector operates at the network layer, leveraging the inherent trust placed in DHCP communications to compromise systems. The vulnerability affects Android systems through version 5.0, but also extends to other products using dhcpcd 5.x versions, creating a widespread attack surface. According to ATT&CK framework, this vulnerability aligns with T1059.007 for command and script interpreter, as successful exploitation could enable attackers to execute arbitrary commands on affected systems, and T1499.004 for network denial of service, as the vulnerability can also cause system instability through memory corruption.
Mitigation strategies for CVE-2014-7913 should prioritize immediate patching of affected dhcpcd versions to 6.9.2 or later, which contains the necessary fixes for proper snprintf return value handling. System administrators should implement network segmentation and DHCP server authentication mechanisms to reduce exposure to malicious DHCP servers. The implementation of DHCP snooping and DHCP server validation can help prevent unauthorized DHCP servers from influencing network clients. Additionally, monitoring network traffic for anomalous DHCP option patterns and implementing intrusion detection systems can help identify exploitation attempts. Organizations should also consider disabling unnecessary DHCP client functionality on systems where it is not required, reducing the attack surface. The fix implemented in patched versions properly validates the return value from snprintf and ensures that buffer boundaries are respected, preventing the memory corruption that leads to arbitrary code execution or denial of service conditions.