Source URL: https://blog.talosintelligence.com/small-praise-for-modern-compilers-a-case-of-ubuntu-printing-vulnerability-that-wasnt/
Source: Cisco Talos Blog
Title: Small praise for modern compilers – A case of Ubuntu printing vulnerability that wasn’t
Feedly Summary: By Aleksandar NikolichEarlier this year, we conducted code audits of the macOS printing subsystem, which is heavily based on the open-source CUPS package. During this investigation, IPP-USB protocol caught our attention. IPP over USB specification defines how printers that are available over USB can only still support network printing
AI Summary and Description: Yes
Summary: The text discusses a vulnerability discovered in the IPP-USB handling of the Ubuntu operating system, specifically within the `ippusbxd` package. This vulnerability, linked to potential buffer overflow, is mitigated by modern compiler features and is relatively minor due to the lack of exploitation avenues and an upcoming safer alternative.
Detailed Description:
– The investigation began with code audits of the macOS printing subsystem, focusing on the IPP-USB protocol, which facilitates network printing via USB printers.
– The research then shifted to examine how Ubuntu 22.04 managed this functionality through the `ippusbxd` package, part of the OpenPrinting suite.
– The `ippusbxd` package was scrutinized due to several high-severity vulnerabilities affecting the suite recently, raising alarms within the developer community, but mitigating factors indicate the overall threat level may not be catastrophic.
– Key Findings:
– **Vulnerability Discovery**: Rooted in improper use of the `strncpy` function, leading to a stack-based buffer overflow if a printer reports overly large media dimensions.
– **Compiler Warnings**: Messages from the compiler indicate risks, emphasizing the importance of thorough code analysis.
– **Exploitation Risks**: The potential exploitation of this vulnerability requires a malicious printer to be directly connected, thus significantly limiting the threat.
– **Proof of Concept (PoC)**: Developers demonstrated the vulnerability by creating a proof of concept using Raspberry Pi Zero to act as a malicious USB printer. The demonstration triggered a segmentation fault due to buffer overflow, but the protections built into modern compilers (e.g., FORTIFY_SOURCE) prevented further exploitation.
– **Conclusion and Recommendations**:
– Despite the potential seriousness of buffer overflow vulnerabilities, the combination of compiler features and programming best practices led to effective mitigation.
– Adoption of safer packages like `ipp-usb` is recommended for better security practices.
– Developers should take compiler warnings seriously to preemptively address issues before they become exploitable vulnerabilities.
Overall, the text serves as a valuable case study for security and compliance professionals in examining the efficacy of modern security practices in software development, highlighting the importance of vigilance, code auditing, and the use of advanced compiler features to reduce vulnerability risks.