CVE-2017-16229 in Ox Gem
Summary
by MITRE
In the Ox gem 2.8.1 for Ruby, the process crashes with a stack-based buffer over-read in the read_from_str function in sax_buf.c when a crafted input is supplied to sax_parse.
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Analysis
by VulDB Data Team • 02/10/2023
The vulnerability identified as CVE-2017-16229 represents a critical stack-based buffer over-read flaw within the Ox gem version 2.8.1 for Ruby. This issue specifically manifests in the read_from_str function located within the sax_buf.c file of the Ox parsing library. The vulnerability arises when the gem processes crafted input data through the sax_parse function, leading to unpredictable behavior and potential system instability. The Ox gem serves as a high-performance xml parser for ruby applications, making this vulnerability particularly concerning for systems relying on xml processing. The buffer over-read occurs due to inadequate bounds checking during string parsing operations, where the function attempts to read beyond the allocated memory boundaries.
The technical exploitation of this vulnerability follows a classic buffer over-read pattern that aligns with CWE-125, which describes out-of-bounds read conditions in software systems. When maliciously crafted xml data is fed into the sax_parse function, the read_from_str implementation fails to properly validate input length against available buffer space. This allows an attacker to manipulate the parsing process such that memory locations beyond the intended buffer are accessed, potentially exposing sensitive data or causing application crashes. The stack-based nature of the vulnerability means that the over-read occurs on the program stack, which can lead to information disclosure or denial of service conditions. The flaw demonstrates poor memory management practices and inadequate input sanitization within the xml parsing pipeline.
The operational impact of CVE-2017-16229 extends beyond simple application crashes to potentially enable more sophisticated attack vectors. Systems utilizing the Ox gem for xml processing become vulnerable to denial of service attacks that can bring services offline, or in more severe cases, may allow for information disclosure through stack memory exposure. The vulnerability affects ruby applications that depend on Ox for parsing xml data, including web applications, api services, and data processing systems. From an ATT&CK framework perspective, this vulnerability could be leveraged as part of a broader attack chain under the T1203 - Exploitation for Privilege Escalation or T1499 - Endpoint Termination techniques, depending on how the vulnerability is exploited within a larger attack scenario. The impact is particularly severe in environments where xml parsing is a common operation and where the application does not properly validate or sanitize external input.
Mitigation strategies for this vulnerability require immediate patching of the Ox gem to version 2.8.2 or later, which contains the necessary fixes for the buffer over-read condition. Organizations should conduct comprehensive vulnerability assessments to identify all systems running affected versions of the gem and prioritize remediation efforts. Input validation should be strengthened at multiple levels, including implementing proper xml schema validation and sanitizing all external xml data before processing. Network segmentation and application-level firewalls can help limit the impact if exploitation occurs. Additionally, monitoring systems should be configured to detect unusual parsing behavior or application crashes that may indicate exploitation attempts. The vulnerability highlights the importance of regular security updates and proper code review practices, particularly for libraries handling external data parsing. Organizations should also consider implementing runtime protections such as address space layout randomization and stack canaries to mitigate potential exploitation scenarios.