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Sayfer Blog

Blog about security, malware and how to make our internet Sayfer.

  • IDOR – Insecure Direct Object Reference
    June 28, 2021
    IDOR - Insecure Direct Object Reference
    Insecure Direct Object Reference or IDOR happens when an application inadvertently exposes private objects through user input. For example, a website may let you access private customer profiles by entering unique user IDs into the URL like this: https://example.com/account?id=32145 The danger, of course, is that an attacker might create a bot that ...
  • Security Considerations During Authentication
    May 13, 2021
    Security Considerations During Authentication
    One of the most prolific vectors for security vulnerabilities in applications and websites is authentication – login. Gaining access to important data and functionalities could be very profitable, so compromising users’ credentials are a prime target as we have seen in the past. Here are a couple of pitfalls to ...
  • We Found a Pre-Released WhatsApp Feature
    April 21, 2021
    We Found a Pre-Released WhatsApp Feature
    While researching WhatsApp web for a project that we’ll write about soon, we accidentally found that WhatsApp has a feature flag for a hidden feature – one that allows users to change the playback rate of voice messages. Broken Behavior One of our research tools allows us to change the playback rate ...
  • 3 Vulnerabilities in Kaspersky-backed TinyCheck
    February 11, 2021
    3 Vulnerabilities in Kaspersky-backed TinyCheck
    In our latest research, we found 3 different vulnerabilities in TinyCheck, an open-source tool developed and published by Félix Aimé, one of Kaspersky’s GReAT experts. Each one of the vulnerabilities has a high severity by itself. Once combined into a chain, a remote attacker could exploit it to get an ...
  • Fuzzing Part 2 – Fuzzing with AFL
    February 2, 2021
    Fuzzing Part 2 - Fuzzing with AFL
    As I wrote in the last chapter, in this article I will only explain how to fuzz when there’s access to the source code using AFL. To demonstrate, I took an old open-source program that I found on GitHub called ccalc. As the name suggests, it is a simple calculator ...
  • Fuzzing Part 1: The Theory
    January 28, 2021
    Fuzzing Part 1: The Theory
    Fuzzing First of all, what is fuzzing exactly? When we fuzz test a program or function that receives input (any type of input), we try different combinations of input until we get a crush or another desired result (frequently memory leaks). When a program doesn’t sanitize its input properly, malformed or ...
  • Detecting Dynamic Loading in Android Applications With /proc/maps
    November 4, 2020
    Detecting Dynamic Loading in Android Applications With /proc/maps
    TL;DR: Through dynamic loading, malware authors can covertly load malicious code into their application in order to avoid detection. We can detect such loading through the application’s /proc//maps kernel generated file.Recently, we created a simple script that allows us to detect dynamic loading in Android apps. This presented us with ...
  • A Technical Analysis of the 4k Facebook Scam
    September 15, 2020
    A Technical Analysis of the 4k Facebook Scam
    tl;dr: Don’t trust webview logins on native apps, they can read your cookies and use them to their advantage. Following the Hacker News thread “How I lost €4k in a Facebook scam“, we reverse engineered the app to see how this happens. The new phishing wave Phishing. We all know it, we ...
  • Android Firmware Exploitation – Unsigned Firmware in Samsung’s SoC CVE-2020-10831
    September 1, 2020
    Android Firmware Exploitation -  Unsigned Firmware in Samsung's SoC CVE-2020-10831
    TL;DR   We will explain how we exploited Android firmware using an undocumented kernel API that was found by reverse-engineering Samsung’s “Hidden Factory Settings” app.This API permits flashing unsigned firmware of Samsung’s touchscreen firmware.The CVE affects all Samsung S7-S10 series using exynos chipset. Inspiration   After reading project zero’s great article about exploiting WiFi firmware ...
  • Tracing Android Applications With Termux and Linux Utilities
    June 6, 2020
    Tracing Android Applications With Termux and Linux Utilities
    The following article will demonstrate how to use “old fashioned” Linux utilities and Termux to trace Android apps. We’ll use Termux linux VM inside an Android device in order to install common Linux utils alongside Android Apps. The main tools we will use are: Strace Jtrace Inotifywatch *Rooted device is needed What is Termux Termux is a terminal ...