论文标题

pthammer:通过隐式访问的跨用户 - 内 - 内尔 - 荷叶锤

PThammer: Cross-User-Kernel-Boundary Rowhammer through Implicit Accesses

论文作者

Zhang, Zhi, Cheng, Yueqiang, Liu, Dongxi, Nepal, Surya, Wang, Zhi, Yarom, Yuval

论文摘要

Rowhammer是DRAM内存中的硬件漏洞,在此重复访问内存可以在附近的内存位置诱导位。作为硬件漏洞,Rowhammer绕过了所有系统内存保护,使对手能够损害数据的完整性和机密性。 Rowhammer攻击已显示出可以使特权升级,沙盒逃生和加密密钥披露。最近,一些建议建议利用访问的内存位置与位置的位置之间的空间接近度,以防止对Rowhammer进行防御。这些旨在拒绝攻击者访问敏感数据附近的内存位置的许可。在本文中,我们质疑这些防御能力的核心假设。我们提出了Pthammer,这是一种混乱的攻击,可导致访问攻击者无法访问的内存位置。具体而言,Pthammer利用现代处理器的地址翻译过程,诱导处理器生成对受保护的存储位置的频繁访问。我们实施了pthammer,证明这是一种可行的攻击,导致系统妥协(例如内核特权升级)。我们进一步评估了拟议的仅软件防御能力的有效性,表明Pthammer可以克服这些防御。

Rowhammer is a hardware vulnerability in DRAM memory, where repeated access to memory can induce bit flips in neighboring memory locations. Being a hardware vulnerability, rowhammer bypasses all of the system memory protection, allowing adversaries to compromise the integrity and confidentiality of data. Rowhammer attacks have shown to enable privilege escalation, sandbox escape, and cryptographic key disclosures. Recently, several proposals suggest exploiting the spatial proximity between the accessed memory location and the location of the bit flip for a defense against rowhammer. These all aim to deny the attacker's permission to access memory locations near sensitive data. In this paper, we question the core assumption underlying these defenses. We present PThammer, a confused-deputy attack that causes accesses to memory locations that the attacker is not allowed to access. Specifically, PThammer exploits the address translation process of modern processors, inducing the processor to generate frequent accesses to protected memory locations. We implement PThammer, demonstrating that it is a viable attack, resulting in a system compromise (e.g., kernel privilege escalation). We further evaluate the effectiveness of proposed software-only defenses showing that PThammer can overcome those.

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