ios kernel exploit
The vulnerability is triggered to drop a reference on port A, and the ports surrounding A are freed, leading to a dangling port pointer. However, the way the vouchers store their entries on that upper level is not really relevant to the study of CVE-2021-1782, so we will pass on it. It works by converting the bits in the PTE that typically directly specify the access permissions into an index into a special register containing the true access permissions; changing the register value swaps protections on all pages mapped with the same access permissions index. IOSurfaceRootUserClient::s_set_surface_notify(), that causes an extra reference to be dropped on a Mach port. This isn't your typical P0 blog post: There is no gripping zero-day exploitation, or novel exploitation research, or thrilling malware reverse engineering. Kernel exploits are very rare. On the other hand elem->e_made is incremented via user_data_get_value() when we create a voucher with the MACH_VOUCHER_ATTR_REDEEM or MACH_VOUCHER_ATTR_USER_DATA_STORE. For instance "bank" attribute is accessed through the MACH_VOUCHER_ATTR_KEY_BANK. Security researcher ModernPwner recently made public cicuta_virosa – a new kernel-level local privilege escalation exploit for iOS 14.3 and below operating systems. More interestingly, we see ivace_refs and ivace_made. Besides being a race condition reported by an anonymous researcher, there is not much details on CVE-2021-1782. This is used to prevent the kernel from dereferencing attacker-supplied pointers to data structures in userspace. One example of an exploit technique is Return-Oriented Programming (ROP), which turns arbitrary PC control into (nearly) arbitrary code execution by reusing executable code gadgets. Pangu jailbreak for iOS 9 was the last untethered jailbreak, so an untethered iOS 11.2.2 – iOS 11 jailbreak would be great news for jailbreakers. TL/DR: You have to race twice to exploit the bug, the PoC is at the end or there. An anonymous researcher identified bugs in the software’s kernel and WebKit browser engine that are likely part of an exploit chain. The exception message is received and the pipe is rewritten to convert the fake port into a kernel read primitive using, . Apple's A7 processor was the first 64-bit, ARMv8-A processor in an iPhone. : Two Mach ports, port A and port B, are allocated as part of a spray. Last, but not least, a control port (ipc_voucher_attr_control_t) is also linked with each attributes but this is out of this post's scope. Other primitives exist for establishing shared memory mappings between userspace and the kernel, which can also be used to work around PAN. An iOS kernel exploit designated to work on all iOS devices <= 10.3.1 - doadam/ziVA , disclosing the value of the target port pointer. So far, we know that ivace->ivace_made is incremented in ivace_reference_by_value(). Indeed, there is another tricky race condition that allows to bring back the sync, between the tempered user_data_element_t and its ivac_entry_t while making the ivac releasable. We do not think there is a real issue when a prior desynchronization (caused by the vulnerability) is not doable. It is a strong form of W^X protection enforced by the MMU and the memory controller over a single span of contiguous memory covering the read-only parts of the kernelcache image and some sensitive data structures like top-level page tables and the trust cache. The notes were updated later to include more details on the other issues. The notes were updated later to include more details on the other issues. An oversight in the implementation led to a trivial bypass when objects are allocated outside of the. Because the voucher layer has no idea how the value is stored by the attribute manager, this feature is usually found on both layers. The Kernel base will be required, especially since I need to patch a few things up. The data buffer is freed and reallocated again such that calling an external method will execute the, gadget, leading to an arbitrary read-then-write that stores the address of the kernel task port in the current task's list of special ports. The boundary between which parts of the exploit are specific to the vulnerability and which parts are generic enough to be considered part of the overall flow is subjective. APRR on its own does not provide any security boundaries, but it makes it possible to segment privilege levels inside a single address space. Filling the hole overlaps the original (partially freed), header of the replacement, such that receiving the message on the original port reads the contents of the replacement, header. Congrats to them! The. A large number of, objects are sprayed and the vulnerability is triggered to decrease the reference count on a voucher and free it. None of the exploits in this list are affected by the presence of stack canaries as they do not target stack buffer overflow vulnerabilities. To establish that we must understand the refcounting semantics of the .ivace_refs. whose fields can be directly read and written from userspace. This key is used to specify which attribute a function should work on, but more on that later. : CVE-2016-7644 is a race condition in XNU's. Works on A7 - A11 devices (no A12 as I have no A12 device). The ports are freed by dropping a stashed reference, leaving the process holding, : A zone garbage collection is forced by calling. The slot is reallocated again with an OOL ports array containing a single target Mach port pointer and the contents are read in userspace via, properties, yielding the address of the port. Clément Lecigne. The freed, slot is reallocated with sprayed pipe buffers. Relevant kernel objects are located and the fake port is converted into a fake map port to remap the fake port into userspace, removing the need to reallocate it. CVE-2020-27932 - iOS kernel type confusion with turnstiles Piercing defenses The complex chain of exploits is required to break through layers … is an ARMv8.3-A security feature that mitigates pointer tampering by storing a cryptographic signature of the pointer value in the upper bits of the pointer. pointer to point to point into the pipe buffers. Any exploit after iOS 10.3 needs to build a fake kernel task port instead. that leaks kernel pointers by failing to fully initialize heap memory before copying out the contents to userspace. The remaining vouchers on the page are freed and a zone garbage collection is forced, leaving a, : The dangling voucher is reallocated by an, is called to obtain a send right to a newly allocated voucher port for the voucher, which causes a pointer to the voucher port to be stored in the fake voucher overlapping the, property discloses the address of the voucher port. Finally, a. : The exploit does not work with PAN enabled. To that end, I have decided to ascribe the following terms specific meanings for the context of this post. It is heavily used by PPL to create a security boundary within the iOS kernel. ) The iOS 8.4.1 Kernel is randomized using kASLR by iBoot at every boot of the system so we’ll need to calculate the randomized address of the components we wanna patch. Behind a voucher, various kind of resources can be referenced. That said, modern iOS kernel exploits are so far unaffected by PPL. )
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