Php 7.1.33 Exploit Github

[Zee Petty]

Idiscovered this bug while I was preparing for my presentation at Black Hat EU 2021. I wanted to include a demo of an exploit that I wrote about in a blog post last year. As I was testing the demo, I noticed that accountsservice was sometimes crashing for the wrong reason. That is, it was crashing due to a different bug than the one that I had deliberately reinserted for the purposes of the demo. I soon discovered that the same reproduction steps also worked on a fully patched version of accountsservice.

When I first started working on an exploit for this vulnerability, it felt like a long shot. I estimated my chances of success at less than 25% when I discussed it with my colleagues. The main difficulty is that the bug only affects a single 0x20-sized memory chunk.

Sometimes this enables me to leak an address, but only when the bytes of the address form a valid UTF-8 string, so it only works occasionally. In the end, though, I decided that this infoleak was unlikely to be useful. The problem is that, even if I know the ASLR offsets, my ability to overwrite the memory is very limited because I can only mess with a single 0x20-sized chunk. Furthermore, the UTF-8 restriction also limits my ability to send a forged pointer back.

I think this exploit is an interesting example of exploiting a memory management bug purely through application logic, rather than, for example, by using any of the traditional Malloc Maleficarum techniques (that work by overwriting the heap metadata). An increasing number of mitigations have been added to the glibc malloc implementation to thwart those traditional techniques, but none of them are able to prevent a data-driven exploit like this one. Instead, the exploit uses its influence on the target process to carve an unintended, but feasible, logic path through the application to achieve its goals. This approach to memory management exploitation can provide many opportunities for attackers to take advantage of even the smallest issues in a targeted application, unhindered by any execution flow integrity mitigations.

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In addition, exploiting this bypass can also result in a takeover of popular GitHub actions, which are also consumed by specifying a GitHub namespace. Poisoning a popular GitHub action could lead to major Supply Chain attacks with significant repercussions.

Recent research by Aqua has revealed that organizations as large as Google and Lyft were vulnerable to this form of attack. This underscores the critical nature of the vulnerability, as it could potentially impact some of the biggest players in the tech industry, who have promptly mitigated the risks after being notified.

The new exploitation method takes advantage of a potential race condition between the creation of a repository and the renaming of a username. Checkmarx SCS Group Architect, Elad Rapoport, has been able to demonstrate how he was able to bypass GitHub checks by almost simultaneously creating a repository and changing the username.

Additionally, consider using ChainJacking ( ) which is an open-source project developed by Checkmarx, designed to help you realize if any of your Go lang direct GitHub dependencies is susceptible to the RepoJacking attack.

Nightmare is an intro to binary exploitation / reverse engineering course based around ctf challenges. I call it that because it's a lot of people's nightmare to get hit by weaponized 0 days, which these skills directly translate into doing that type of work (plus it's a really cool song).

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