Abdelrahman Ibrahem

Operating Systems | Security | Distributed Systems

[Abdelrahman Ibrahem @_aibrahem]

@nomadgoods Hi, i sent both a support DM and email last week. Could you please respond.

[Abdelrahman Ibrahem @_aibrahem]

@ics Hi, I wanted to check the status of my Chargeback request.

[Abdelrahman Ibrahem @_aibrahem]

@akram_abunahla @MahSayedSalem That’s exactly what should be happening, we should have non-profit, non governmental organizations actually doing these kind of audits.

[Abdelrahman Ibrahem @_aibrahem]

@akram_abunahla @MahSayedSalem No, I don’t. But I also believe most people really don’t care so much about privacy.

[Abdelrahman Ibrahem @_aibrahem]

@MahSayedSalem @akram_abunahla PGP has been used before online privacy laws was ever a thing.

[Abdelrahman Ibrahem @_aibrahem]

@akram_abunahla @MahSayedSalem For the user friendliness, you can always generate a default key pair, and people who really care about their privacy can generate their own keys and verify the hash offline.

[Abdelrahman Ibrahem @_aibrahem]

@akram_abunahla @MahSayedSalem But Threema’s backend is closed source, right? And even if it’s not, how would you know that the actual released source code is the one running.

[Abdelrahman Ibrahem @_aibrahem]

@MahSayedSalem Developers can use E2E encryption with the ability for users to upload thier own keys to make sure no one is eavesdropping. I think Element does this (based on the Matrix protocol).

[Abdelrahman Ibrahem @_aibrahem]

@ahmdelemam Unused RAM is wasted RAM

[Ahmed Elemam @ahmdelemam]

إحنا كل اللي يهمنا سعادة بنتنا و آخر حاجة نتكلم فيها الفلوس، و حيث إن سعادتها مرتبطة بيها فنتكلم في الفلوس.

حلقة جديدة من Tech Podcast بالعربي

لايف مع عدوي و سالم و حديث عن

مرتبات التيك في مصر و فكرة https://t.co/5cx8jeZt3N

https://t.co/FKXQ5QMwQ3

غداً إن شاء الله في العاشرة مساءً بتوقيت مصر

[Abdelrahman Ibrahem @_aibrahem]

@ahmdelemam @Abdelra23757769 I really enjoy these kinds of questions. My go-to question for junior/senior positions is, 'How would you implement malloc?' The answer could range from 'I'd use mmap' to a discussion of the security implications of a fastbin implementation.

[0xor0ne @0xor0ne]

A couple of blog posts for learning about Linux process injection
(specifically sshd injection for credential harvesting)

@_xpn_: https://t.co/1eIYm48xIO
@jm33_m0: https://t.co/VQrBwL4b28

#processinjection #redteam #cybersecurity

[Abdelrahman Ibrahem @_aibrahem]

@AlaaAttya @rgbdev The concept of "Thread" is just an operating system construct. It can mean whatever the OS developer wants it to mean.

[Abdelrahman Ibrahem @_aibrahem]

@AlaaAttya @rgbdev So while you think you're executing one (or two) threads on each core, your actually executing interposing instructions that could belong to a bunch of different threads.

[Abdelrahman Ibrahem @_aibrahem]

@rgbdev @AlaaAttya I think I miss-spoke. The linux kernel scheduler does seem to have SMT awareness, probably preventing CPU bound tasks from being scheduled on the same core. But as far as userspace is concerned they’re just regular threads.

[Abdelrahman Ibrahem @_aibrahem]

@rgbdev @AlaaAttya I think most operating systems don’t differentiate between the two. Other than research OS’s I’m not sure I’ve ever seen an operating system scheduler taking SMT into account.

[Abdelrahman Ibrahem @_aibrahem]

@rgbdev @AlaaAttya Also this is just a “model” of how things are supposed to work. In the real world your CPU probably has super scaler OOO cores that are executing instructions from multiple threads in parallel.