CVE-2010-4076 in Linux
Summary
by MITRE
The rs_ioctl function in drivers/char/amiserial.c in the Linux kernel 2.6.36.1 and earlier does not properly initialize a certain structure member, which allows local users to obtain potentially sensitive information from kernel stack memory via a TIOCGICOUNT ioctl call.
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Analysis
by VulDB Data Team • 07/01/2024
The vulnerability identified as CVE-2010-4076 resides within the Linux kernel's serial driver implementation, specifically in the rs_ioctl function located in drivers/char/amiserial.c. This flaw represents a classic information disclosure issue that arises from improper initialization of kernel data structures. The vulnerability affects Linux kernel versions up to and including 2.6.36.1, making it a significant concern for systems running older kernel versions. The issue manifests when a local user executes a TIOCGICOUNT ioctl call against a serial device, which triggers the flawed rs_ioctl function and subsequently exposes kernel stack memory contents to unauthorized access.
The technical root cause of this vulnerability stems from a failure to properly initialize a structure member within the rs_ioctl function. According to CWE-248, this represents an improper initialization flaw that allows attackers to read uninitialized memory contents. When the TIOCGICOUNT ioctl command is processed, the function fails to initialize certain fields of the structure before returning data to user space. This uninitialized memory may contain remnants of previous kernel operations, including sensitive data such as cryptographic keys, passwords, or other confidential information that was previously stored in the same memory locations. The vulnerability operates at the kernel level, making it particularly dangerous as it can be exploited by any local user with access to the system, regardless of their privilege level.
The operational impact of CVE-2010-4076 extends beyond simple information disclosure, as it can potentially expose sensitive kernel memory contents that might include system credentials, encryption keys, or other confidential data. This type of vulnerability aligns with ATT&CK technique T1005, which involves data from local system sources, and can be leveraged as a reconnaissance step by attackers seeking to gather intelligence about the target system. Local privilege escalation remains a potential concern, as the leaked information could be used to construct more sophisticated attacks or to bypass security controls. The vulnerability is particularly concerning in multi-tenant environments or systems where local users might have limited access but could exploit this flaw to gain insights into other processes or system configurations.
Mitigation strategies for CVE-2010-4076 primarily focus on kernel version updates, as the vulnerability was resolved in kernel versions 2.6.37 and later. System administrators should prioritize patching affected systems with the latest kernel releases to eliminate this exposure. Additionally, implementing proper access controls and limiting local user privileges can reduce the attack surface, though this does not eliminate the vulnerability itself. The fix for this issue involved ensuring proper initialization of the affected structure member before the TIOCGICOUNT ioctl call returns data to user space. Organizations should also consider monitoring for suspicious ioctl activity patterns and implementing kernel hardening measures such as stack canaries and address space layout randomization to further reduce the potential impact of similar vulnerabilities. Regular security assessments and kernel security audits should be conducted to identify and remediate similar initialization flaws that could exist in other kernel subsystems.