CVE-2010-3301 in Linux
Summary
by MITRE
The IA32 system call emulation functionality in arch/x86/ia32/ia32entry.S in the Linux kernel before 2.6.36-rc4-git2 on the x86_64 platform does not zero extend the %eax register after the 32-bit entry path to ptrace is used, which allows local users to gain privileges by triggering an out-of-bounds access to the system call table using the %rax register. NOTE: this vulnerability exists because of a CVE-2007-4573 regression.
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Analysis
by VulDB Data Team • 12/08/2024
The vulnerability described in CVE-2010-3301 represents a critical privilege escalation flaw within the Linux kernel's system call handling mechanism on x86_64 platforms. This issue specifically affects kernel versions prior to 2.6.36-rc4-git2 and stems from improper register handling during the transition from 32-bit to 64-bit system call execution paths. The vulnerability manifests in the arch/x86/ia32/ia32entry.S file where the IA32 system call emulation functionality fails to properly zero-extend the %eax register after processing 32-bit ptrace operations. This regression was introduced due to the reoccurrence of issues similar to CVE-2007-4573, which had previously been addressed but subsequently reappeared in the codebase.
The technical flaw exploits a fundamental issue in register management during system call emulation where the %rax register, which serves as the 64-bit general-purpose register, retains high-order bits from previous operations when the system call path transitions from 32-bit to 64-bit execution modes. When a local user executes a ptrace operation that triggers the 32-bit entry path, the %eax register containing the system call number is not properly zero-extended to fill the entire %rax register. This incomplete zero-extension results in the high-order bits of %rax containing arbitrary data that can be interpreted as an index into the system call table. The vulnerability specifically leverages the fact that the ptrace system call can be manipulated to cause an out-of-bounds access to the system call table, which is typically protected from direct user access.
The operational impact of this vulnerability is severe and directly enables local privilege escalation attacks. An attacker with user-level privileges can exploit this flaw to execute arbitrary system calls with elevated privileges, effectively bypassing the kernel's security boundaries. The vulnerability requires local access and does not involve network exposure, but it can be particularly dangerous in multi-user environments where attackers might have limited user access initially. The privilege escalation occurs because the out-of-bounds access to the system call table allows the attacker to map arbitrary system call numbers that correspond to privileged operations, such as those that modify kernel memory or gain root access. This represents a classic case of a kernel memory corruption vulnerability that can be leveraged for complete system compromise.
The vulnerability demonstrates characteristics consistent with CWE-125, which describes out-of-bounds read conditions, and aligns with ATT&CK techniques related to privilege escalation and kernel exploitation. The flaw essentially creates a situation where a 32-bit value is improperly extended to 64-bit context, leading to memory access violations that can be manipulated for malicious purposes. The attack vector specifically targets the ptrace system call which is designed for process tracing and debugging but becomes exploitable due to the register handling error. Mitigation strategies should focus on applying the kernel patch that properly zero-extends the %eax register during system call entry transitions, ensuring that the high-order bits of %rax are cleared when entering the 64-bit system call handling path. Additionally, system administrators should monitor for any instances of ptrace usage in production environments and consider implementing additional security controls to limit potential exploitation vectors. This vulnerability underscores the importance of careful register handling in kernel code and the potential for seemingly minor code regressions to create critical security flaws that can be exploited for complete system compromise.