Biblio

Applications in C/C++ are notoriously prone to memory corruptions. With significant research efforts devoted to this area of study, the security threats posed by previously popular vulnerabilities, such as stack and heap overflows, are not as serious as before. Instead, we have seen the meteoric rise of attacks exploiting use-after-free (UaF) vulnerabilities in recent years, which root in pointers pointing to freed memory (i.e., dangling pointers). Although various approaches have been proposed to harden software against UaF, none of them can achieve robustness and efficiency at the same time. In this paper, we present a novel defense called pSweeper to robustly protect against UaF exploits with low overhead, and pinpoint the root-causes of UaF vulnerabilities with one safe crash. The success of pSweeper lies in its two unique and innovative design ideas, concurrent pointer sweeping (CPW) and object origin tracking (OOT). CPW exploits the increasingly available multi-cores on modern PCs and outsources the heavyweight security checks and enforcement to dedicated threads that can run on spare cores. Specifically, CPW iteratively sweeps all live pointers in a concurrent thread to find dangling pointers. This design is quite different from previous work that requires to track every pointer propagation to maintain accurate point-to relationship between pointers and objects. OOT can help to pinpoint the root-causes of UaF by informing developers of how a dangling pointer is created, i.e., how the problematic object is allocated and freed. We implement a prototype of pSweeper and validate its efficacy in real scenarios. Our experimental results show that pSweeper is effective in defeating real-world UaF exploits and efficient when deployed in production runs.

In a dangling DNS record (Dare), the resources pointed to by the DNS record are invalid, but the record itself has not yet been purged from DNS. In this paper, we shed light on a largely overlooked threat in DNS posed by dangling DNS records. Our work reveals that Dare can be easily manipulated by adversaries for domain hijacking. In particular, we identify three attack vectors that an adversary can harness to exploit Dares. In a large-scale measurement study, we uncover 467 exploitable Dares in 277 Alexa top 10,000 domains and 52 edu zones, showing that Dare is a real, prevalent threat. By exploiting these Dares, an adversary can take full control of the (sub)domains and can even have them signed with a Certificate Authority (CA). It is evident that the underlying cause of exploitable Dares is the lack of authenticity checking for the resources to which that DNS record points. We then propose three defense mechanisms to effectively mitigate Dares with little human effort.