Critical Vulnerability in libseccomp: Bypass of Seccomp Filters Leading to Potential Privilege Escalation
Summary
ALPINE-CVE-2019-9893: libseccomp before 2.4.0 did not correctly generate 64-bit syscall argument comparisons using the arithmetic operators (LT, GT, LE, GE), which might able to lead to bypassing seccomp filters and potential privilege escala... Affects libseccomp versions < 2.4.0-r0. Fixed in 2.4.0-r0. How to fix ↓
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Background
libseccomp is a library that provides an easy way to restrict the actions that a process can take on a Linux system. It allows developers to define a set of rules that specify which system calls a process is allowed to make, enhancing the security of applications by limiting their capabilities. However, prior to version 2.4.0, libseccomp had a flaw that could lead to the bypassing of these filters, exposing systems to potential privilege escalation attacks.
Vulnerability Detail
The vulnerability identified as CVE-2019-9893 in libseccomp arises from improper handling of 64-bit syscall argument comparisons using arithmetic operators such as LT, GT, LE, and GE. This flaw allows attackers to craft inputs that could bypass the seccomp filters, potentially leading to unauthorized access and privilege escalation. The vulnerability has a CVSS score of 9.8, indicating its critical severity and the significant risk it poses to affected systems.
How To Fix
Minimum fixed version
2.4.0-r0
This is the first release that contains the fix.
sudo apk add --upgrade libseccompTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, consider implementing stricter input validation and monitoring system calls to detect any unusual behavior. However, the best course of action is to apply the patch as soon as possible.
Conclusion
The CVE-2019-9893 vulnerability in libseccomp poses a significant risk to systems using versions prior to 2.4.0. It is crucial to update to the patched version to safeguard against potential privilege escalation attacks. Regular monitoring and vulnerability management practices, such as using tools like Vulert, can help maintain application security.
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FAQ
CVE-2019-9893 is a critical vulnerability in the libseccomp library that allows attackers to bypass seccomp filters, potentially leading to privilege escalation.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
The CVSS score of CVE-2019-9893 is 9.8, indicating a critical level of severity.
Update libseccomp to version 2.4.0-r0 or later using the command: apk upgrade libseccomp.
If exploited, this vulnerability could allow attackers to bypass security restrictions and gain unauthorized access to system resources, leading to privilege escalation.
References
Related vulnerabilities
Recent vulnerabilities recorded for libseccomp.
