🤖
hacktricks
  • 👾Welcome!
    • HackTricks
    • HackTricks Values & FAQ
    • About the author
  • 🤩Generic Methodologies & Resources
    • Pentesting Methodology
    • External Recon Methodology
      • Wide Source Code Search
      • Github Dorks & Leaks
    • Pentesting Network
      • DHCPv6
      • EIGRP Attacks
      • GLBP & HSRP Attacks
      • IDS and IPS Evasion
      • Lateral VLAN Segmentation Bypass
      • Network Protocols Explained (ESP)
      • Nmap Summary (ESP)
      • Pentesting IPv6
      • WebRTC DoS
      • Spoofing LLMNR, NBT-NS, mDNS/DNS and WPAD and Relay Attacks
      • Spoofing SSDP and UPnP Devices with EvilSSDP
    • Pentesting Wifi
      • Evil Twin EAP-TLS
    • Phishing Methodology
      • Clone a Website
      • Detecting Phishing
      • Phishing Files & Documents
    • Basic Forensic Methodology
      • Baseline Monitoring
      • Anti-Forensic Techniques
      • Docker Forensics
      • Image Acquisition & Mount
      • Linux Forensics
      • Malware Analysis
      • Memory dump analysis
        • Volatility - CheatSheet
      • Partitions/File Systems/Carving
        • File/Data Carving & Recovery Tools
      • Pcap Inspection
        • DNSCat pcap analysis
        • Suricata & Iptables cheatsheet
        • USB Keystrokes
        • Wifi Pcap Analysis
        • Wireshark tricks
      • Specific Software/File-Type Tricks
        • Decompile compiled python binaries (exe, elf) - Retreive from .pyc
        • Browser Artifacts
        • Deofuscation vbs (cscript.exe)
        • Local Cloud Storage
        • Office file analysis
        • PDF File analysis
        • PNG tricks
        • Video and Audio file analysis
        • ZIPs tricks
      • Windows Artifacts
        • Interesting Windows Registry Keys
    • Brute Force - CheatSheet
    • Python Sandbox Escape & Pyscript
      • Bypass Python sandboxes
        • LOAD_NAME / LOAD_CONST opcode OOB Read
      • Class Pollution (Python's Prototype Pollution)
      • Python Internal Read Gadgets
      • Pyscript
      • venv
      • Web Requests
      • Bruteforce hash (few chars)
      • Basic Python
    • Exfiltration
    • Tunneling and Port Forwarding
    • Threat Modeling
    • Search Exploits
    • Reverse Shells (Linux, Windows, MSFVenom)
      • MSFVenom - CheatSheet
      • Reverse Shells - Windows
      • Reverse Shells - Linux
      • Full TTYs
  • 🐧Linux Hardening
    • Checklist - Linux Privilege Escalation
    • Linux Privilege Escalation
      • Arbitrary File Write to Root
      • Cisco - vmanage
      • Containerd (ctr) Privilege Escalation
      • D-Bus Enumeration & Command Injection Privilege Escalation
      • Docker Security
        • Abusing Docker Socket for Privilege Escalation
        • AppArmor
        • AuthZ& AuthN - Docker Access Authorization Plugin
        • CGroups
        • Docker --privileged
        • Docker Breakout / Privilege Escalation
          • release_agent exploit - Relative Paths to PIDs
          • Docker release_agent cgroups escape
          • Sensitive Mounts
        • Namespaces
          • CGroup Namespace
          • IPC Namespace
          • PID Namespace
          • Mount Namespace
          • Network Namespace
          • Time Namespace
          • User Namespace
          • UTS Namespace
        • Seccomp
        • Weaponizing Distroless
      • Escaping from Jails
      • euid, ruid, suid
      • Interesting Groups - Linux Privesc
        • lxd/lxc Group - Privilege escalation
      • Logstash
      • ld.so privesc exploit example
      • Linux Active Directory
      • Linux Capabilities
      • NFS no_root_squash/no_all_squash misconfiguration PE
      • Node inspector/CEF debug abuse
      • Payloads to execute
      • RunC Privilege Escalation
      • SELinux
      • Socket Command Injection
      • Splunk LPE and Persistence
      • SSH Forward Agent exploitation
      • Wildcards Spare tricks
    • Useful Linux Commands
    • Bypass Linux Restrictions
      • Bypass FS protections: read-only / no-exec / Distroless
        • DDexec / EverythingExec
    • Linux Environment Variables
    • Linux Post-Exploitation
      • PAM - Pluggable Authentication Modules
    • FreeIPA Pentesting
  • 🍏MacOS Hardening
    • macOS Security & Privilege Escalation
      • macOS Apps - Inspecting, debugging and Fuzzing
        • Objects in memory
        • Introduction to x64
        • Introduction to ARM64v8
      • macOS AppleFS
      • macOS Bypassing Firewalls
      • macOS Defensive Apps
      • macOS GCD - Grand Central Dispatch
      • macOS Kernel & System Extensions
        • macOS IOKit
        • macOS Kernel Extensions & Debugging
        • macOS Kernel Vulnerabilities
        • macOS System Extensions
      • macOS Network Services & Protocols
      • macOS File Extension & URL scheme app handlers
      • macOS Files, Folders, Binaries & Memory
        • macOS Bundles
        • macOS Installers Abuse
        • macOS Memory Dumping
        • macOS Sensitive Locations & Interesting Daemons
        • macOS Universal binaries & Mach-O Format
      • macOS Objective-C
      • macOS Privilege Escalation
      • macOS Process Abuse
        • macOS Dirty NIB
        • macOS Chromium Injection
        • macOS Electron Applications Injection
        • macOS Function Hooking
        • macOS IPC - Inter Process Communication
          • macOS MIG - Mach Interface Generator
          • macOS XPC
            • macOS XPC Authorization
            • macOS XPC Connecting Process Check
              • macOS PID Reuse
              • macOS xpc_connection_get_audit_token Attack
          • macOS Thread Injection via Task port
        • macOS Java Applications Injection
        • macOS Library Injection
          • macOS Dyld Hijacking & DYLD_INSERT_LIBRARIES
          • macOS Dyld Process
        • macOS Perl Applications Injection
        • macOS Python Applications Injection
        • macOS Ruby Applications Injection
        • macOS .Net Applications Injection
      • macOS Security Protections
        • macOS Gatekeeper / Quarantine / XProtect
        • macOS Launch/Environment Constraints & Trust Cache
        • macOS Sandbox
          • macOS Default Sandbox Debug
          • macOS Sandbox Debug & Bypass
            • macOS Office Sandbox Bypasses
        • macOS Authorizations DB & Authd
        • macOS SIP
        • macOS TCC
          • macOS Apple Events
          • macOS TCC Bypasses
            • macOS Apple Scripts
          • macOS TCC Payloads
        • macOS Dangerous Entitlements & TCC perms
        • macOS - AMFI - AppleMobileFileIntegrity
        • macOS MACF - Mandatory Access Control Framework
        • macOS Code Signing
        • macOS FS Tricks
          • macOS xattr-acls extra stuff
      • macOS Users & External Accounts
    • macOS Red Teaming
      • macOS MDM
        • Enrolling Devices in Other Organisations
        • macOS Serial Number
      • macOS Keychain
    • macOS Useful Commands
    • macOS Auto Start
  • 🪟Windows Hardening
    • Checklist - Local Windows Privilege Escalation
    • Windows Local Privilege Escalation
      • Abusing Tokens
      • Access Tokens
      • ACLs - DACLs/SACLs/ACEs
      • AppendData/AddSubdirectory permission over service registry
      • Create MSI with WIX
      • COM Hijacking
      • Dll Hijacking
        • Writable Sys Path +Dll Hijacking Privesc
      • DPAPI - Extracting Passwords
      • From High Integrity to SYSTEM with Name Pipes
      • Integrity Levels
      • JuicyPotato
      • Leaked Handle Exploitation
      • MSI Wrapper
      • Named Pipe Client Impersonation
      • Privilege Escalation with Autoruns
      • RoguePotato, PrintSpoofer, SharpEfsPotato, GodPotato
      • SeDebug + SeImpersonate copy token
      • SeImpersonate from High To System
      • Windows C Payloads
    • Active Directory Methodology
      • Abusing Active Directory ACLs/ACEs
        • Shadow Credentials
      • AD Certificates
        • AD CS Account Persistence
        • AD CS Domain Escalation
        • AD CS Domain Persistence
        • AD CS Certificate Theft
      • AD information in printers
      • AD DNS Records
      • ASREPRoast
      • BloodHound & Other AD Enum Tools
      • Constrained Delegation
      • Custom SSP
      • DCShadow
      • DCSync
      • Diamond Ticket
      • DSRM Credentials
      • External Forest Domain - OneWay (Inbound) or bidirectional
      • External Forest Domain - One-Way (Outbound)
      • Golden Ticket
      • Kerberoast
      • Kerberos Authentication
      • Kerberos Double Hop Problem
      • LAPS
      • MSSQL AD Abuse
      • Over Pass the Hash/Pass the Key
      • Pass the Ticket
      • Password Spraying / Brute Force
      • PrintNightmare
      • Force NTLM Privileged Authentication
      • Privileged Groups
      • RDP Sessions Abuse
      • Resource-based Constrained Delegation
      • Security Descriptors
      • SID-History Injection
      • Silver Ticket
      • Skeleton Key
      • Unconstrained Delegation
    • Windows Security Controls
      • UAC - User Account Control
    • NTLM
      • Places to steal NTLM creds
    • Lateral Movement
      • AtExec / SchtasksExec
      • DCOM Exec
      • PsExec/Winexec/ScExec
      • SmbExec/ScExec
      • WinRM
      • WmiExec
    • Pivoting to the Cloud
    • Stealing Windows Credentials
      • Windows Credentials Protections
      • Mimikatz
      • WTS Impersonator
    • Basic Win CMD for Pentesters
    • Basic PowerShell for Pentesters
      • PowerView/SharpView
    • Antivirus (AV) Bypass
  • 📱Mobile Pentesting
    • Android APK Checklist
    • Android Applications Pentesting
      • Android Applications Basics
      • Android Task Hijacking
      • ADB Commands
      • APK decompilers
      • AVD - Android Virtual Device
      • Bypass Biometric Authentication (Android)
      • content:// protocol
      • Drozer Tutorial
        • Exploiting Content Providers
      • Exploiting a debuggeable application
      • Frida Tutorial
        • Frida Tutorial 1
        • Frida Tutorial 2
        • Frida Tutorial 3
        • Objection Tutorial
      • Google CTF 2018 - Shall We Play a Game?
      • Install Burp Certificate
      • Intent Injection
      • Make APK Accept CA Certificate
      • Manual DeObfuscation
      • React Native Application
      • Reversing Native Libraries
      • Smali - Decompiling/[Modifying]/Compiling
      • Spoofing your location in Play Store
      • Tapjacking
      • Webview Attacks
    • iOS Pentesting Checklist
    • iOS Pentesting
      • iOS App Extensions
      • iOS Basics
      • iOS Basic Testing Operations
      • iOS Burp Suite Configuration
      • iOS Custom URI Handlers / Deeplinks / Custom Schemes
      • iOS Extracting Entitlements From Compiled Application
      • iOS Frida Configuration
      • iOS Hooking With Objection
      • iOS Protocol Handlers
      • iOS Serialisation and Encoding
      • iOS Testing Environment
      • iOS UIActivity Sharing
      • iOS Universal Links
      • iOS UIPasteboard
      • iOS WebViews
    • Cordova Apps
    • Xamarin Apps
  • 👽Network Services Pentesting
    • Pentesting JDWP - Java Debug Wire Protocol
    • Pentesting Printers
    • Pentesting SAP
    • Pentesting VoIP
      • Basic VoIP Protocols
        • SIP (Session Initiation Protocol)
    • Pentesting Remote GdbServer
    • 7/tcp/udp - Pentesting Echo
    • 21 - Pentesting FTP
      • FTP Bounce attack - Scan
      • FTP Bounce - Download 2ºFTP file
    • 22 - Pentesting SSH/SFTP
    • 23 - Pentesting Telnet
    • 25,465,587 - Pentesting SMTP/s
      • SMTP Smuggling
      • SMTP - Commands
    • 43 - Pentesting WHOIS
    • 49 - Pentesting TACACS+
    • 53 - Pentesting DNS
    • 69/UDP TFTP/Bittorrent-tracker
    • 79 - Pentesting Finger
    • 80,443 - Pentesting Web Methodology
      • 403 & 401 Bypasses
      • AEM - Adobe Experience Cloud
      • Angular
      • Apache
      • Artifactory Hacking guide
      • Bolt CMS
      • Buckets
        • Firebase Database
      • CGI
      • DotNetNuke (DNN)
      • Drupal
        • Drupal RCE
      • Electron Desktop Apps
        • Electron contextIsolation RCE via preload code
        • Electron contextIsolation RCE via Electron internal code
        • Electron contextIsolation RCE via IPC
      • Flask
      • NodeJS Express
      • Git
      • Golang
      • GWT - Google Web Toolkit
      • Grafana
      • GraphQL
      • H2 - Java SQL database
      • IIS - Internet Information Services
      • ImageMagick Security
      • JBOSS
      • Jira & Confluence
      • Joomla
      • JSP
      • Laravel
      • Moodle
      • Nginx
      • NextJS
      • PHP Tricks
        • PHP - Useful Functions & disable_functions/open_basedir bypass
          • disable_functions bypass - php-fpm/FastCGI
          • disable_functions bypass - dl function
          • disable_functions bypass - PHP 7.0-7.4 (*nix only)
          • disable_functions bypass - Imagick <= 3.3.0 PHP >= 5.4 Exploit
          • disable_functions - PHP 5.x Shellshock Exploit
          • disable_functions - PHP 5.2.4 ionCube extension Exploit
          • disable_functions bypass - PHP <= 5.2.9 on windows
          • disable_functions bypass - PHP 5.2.4 and 5.2.5 PHP cURL
          • disable_functions bypass - PHP safe_mode bypass via proc_open() and custom environment Exploit
          • disable_functions bypass - PHP Perl Extension Safe_mode Bypass Exploit
          • disable_functions bypass - PHP 5.2.3 - Win32std ext Protections Bypass
          • disable_functions bypass - PHP 5.2 - FOpen Exploit
          • disable_functions bypass - via mem
          • disable_functions bypass - mod_cgi
          • disable_functions bypass - PHP 4 >= 4.2.0, PHP 5 pcntl_exec
        • PHP - RCE abusing object creation: new $_GET["a"]($_GET["b"])
        • PHP SSRF
      • PrestaShop
      • Python
      • Rocket Chat
      • Special HTTP headers
      • Source code Review / SAST Tools
      • Spring Actuators
      • Symfony
      • Tomcat
        • Basic Tomcat Info
      • Uncovering CloudFlare
      • VMWare (ESX, VCenter...)
      • Web API Pentesting
      • WebDav
      • Werkzeug / Flask Debug
      • Wordpress
    • 88tcp/udp - Pentesting Kerberos
      • Harvesting tickets from Windows
      • Harvesting tickets from Linux
    • 110,995 - Pentesting POP
    • 111/TCP/UDP - Pentesting Portmapper
    • 113 - Pentesting Ident
    • 123/udp - Pentesting NTP
    • 135, 593 - Pentesting MSRPC
    • 137,138,139 - Pentesting NetBios
    • 139,445 - Pentesting SMB
      • rpcclient enumeration
    • 143,993 - Pentesting IMAP
    • 161,162,10161,10162/udp - Pentesting SNMP
      • Cisco SNMP
      • SNMP RCE
    • 194,6667,6660-7000 - Pentesting IRC
    • 264 - Pentesting Check Point FireWall-1
    • 389, 636, 3268, 3269 - Pentesting LDAP
    • 500/udp - Pentesting IPsec/IKE VPN
    • 502 - Pentesting Modbus
    • 512 - Pentesting Rexec
    • 513 - Pentesting Rlogin
    • 514 - Pentesting Rsh
    • 515 - Pentesting Line Printer Daemon (LPD)
    • 548 - Pentesting Apple Filing Protocol (AFP)
    • 554,8554 - Pentesting RTSP
    • 623/UDP/TCP - IPMI
    • 631 - Internet Printing Protocol(IPP)
    • 700 - Pentesting EPP
    • 873 - Pentesting Rsync
    • 1026 - Pentesting Rusersd
    • 1080 - Pentesting Socks
    • 1098/1099/1050 - Pentesting Java RMI - RMI-IIOP
    • 1414 - Pentesting IBM MQ
    • 1433 - Pentesting MSSQL - Microsoft SQL Server
      • Types of MSSQL Users
    • 1521,1522-1529 - Pentesting Oracle TNS Listener
    • 1723 - Pentesting PPTP
    • 1883 - Pentesting MQTT (Mosquitto)
    • 2049 - Pentesting NFS Service
    • 2301,2381 - Pentesting Compaq/HP Insight Manager
    • 2375, 2376 Pentesting Docker
    • 3128 - Pentesting Squid
    • 3260 - Pentesting ISCSI
    • 3299 - Pentesting SAPRouter
    • 3306 - Pentesting Mysql
    • 3389 - Pentesting RDP
    • 3632 - Pentesting distcc
    • 3690 - Pentesting Subversion (svn server)
    • 3702/UDP - Pentesting WS-Discovery
    • 4369 - Pentesting Erlang Port Mapper Daemon (epmd)
    • 4786 - Cisco Smart Install
    • 4840 - OPC Unified Architecture
    • 5000 - Pentesting Docker Registry
    • 5353/UDP Multicast DNS (mDNS) and DNS-SD
    • 5432,5433 - Pentesting Postgresql
    • 5439 - Pentesting Redshift
    • 5555 - Android Debug Bridge
    • 5601 - Pentesting Kibana
    • 5671,5672 - Pentesting AMQP
    • 5800,5801,5900,5901 - Pentesting VNC
    • 5984,6984 - Pentesting CouchDB
    • 5985,5986 - Pentesting WinRM
    • 5985,5986 - Pentesting OMI
    • 6000 - Pentesting X11
    • 6379 - Pentesting Redis
    • 8009 - Pentesting Apache JServ Protocol (AJP)
    • 8086 - Pentesting InfluxDB
    • 8089 - Pentesting Splunkd
    • 8333,18333,38333,18444 - Pentesting Bitcoin
    • 9000 - Pentesting FastCGI
    • 9001 - Pentesting HSQLDB
    • 9042/9160 - Pentesting Cassandra
    • 9100 - Pentesting Raw Printing (JetDirect, AppSocket, PDL-datastream)
    • 9200 - Pentesting Elasticsearch
    • 10000 - Pentesting Network Data Management Protocol (ndmp)
    • 11211 - Pentesting Memcache
      • Memcache Commands
    • 15672 - Pentesting RabbitMQ Management
    • 24007,24008,24009,49152 - Pentesting GlusterFS
    • 27017,27018 - Pentesting MongoDB
    • 44134 - Pentesting Tiller (Helm)
    • 44818/UDP/TCP - Pentesting EthernetIP
    • 47808/udp - Pentesting BACNet
    • 50030,50060,50070,50075,50090 - Pentesting Hadoop
  • 🕸️Pentesting Web
    • Web Vulnerabilities Methodology
    • Reflecting Techniques - PoCs and Polygloths CheatSheet
      • Web Vulns List
    • 2FA/MFA/OTP Bypass
    • Account Takeover
    • Browser Extension Pentesting Methodology
      • BrowExt - ClickJacking
      • BrowExt - permissions & host_permissions
      • BrowExt - XSS Example
    • Bypass Payment Process
    • Captcha Bypass
    • Cache Poisoning and Cache Deception
      • Cache Poisoning via URL discrepancies
      • Cache Poisoning to DoS
    • Clickjacking
    • Client Side Template Injection (CSTI)
    • Client Side Path Traversal
    • Command Injection
    • Content Security Policy (CSP) Bypass
      • CSP bypass: self + 'unsafe-inline' with Iframes
    • Cookies Hacking
      • Cookie Tossing
      • Cookie Jar Overflow
      • Cookie Bomb
    • CORS - Misconfigurations & Bypass
    • CRLF (%0D%0A) Injection
    • CSRF (Cross Site Request Forgery)
    • Dangling Markup - HTML scriptless injection
      • SS-Leaks
    • Dependency Confusion
    • Deserialization
      • NodeJS - __proto__ & prototype Pollution
        • Client Side Prototype Pollution
        • Express Prototype Pollution Gadgets
        • Prototype Pollution to RCE
      • Java JSF ViewState (.faces) Deserialization
      • Java DNS Deserialization, GadgetProbe and Java Deserialization Scanner
      • Basic Java Deserialization (ObjectInputStream, readObject)
      • PHP - Deserialization + Autoload Classes
      • CommonsCollection1 Payload - Java Transformers to Rutime exec() and Thread Sleep
      • Basic .Net deserialization (ObjectDataProvider gadget, ExpandedWrapper, and Json.Net)
      • Exploiting __VIEWSTATE knowing the secrets
      • Exploiting __VIEWSTATE without knowing the secrets
      • Python Yaml Deserialization
      • JNDI - Java Naming and Directory Interface & Log4Shell
      • Ruby Class Pollution
    • Domain/Subdomain takeover
    • Email Injections
    • File Inclusion/Path traversal
      • phar:// deserialization
      • LFI2RCE via PHP Filters
      • LFI2RCE via Nginx temp files
      • LFI2RCE via PHP_SESSION_UPLOAD_PROGRESS
      • LFI2RCE via Segmentation Fault
      • LFI2RCE via phpinfo()
      • LFI2RCE Via temp file uploads
      • LFI2RCE via Eternal waiting
      • LFI2RCE Via compress.zlib + PHP_STREAM_PREFER_STUDIO + Path Disclosure
    • File Upload
      • PDF Upload - XXE and CORS bypass
    • Formula/CSV/Doc/LaTeX/GhostScript Injection
    • gRPC-Web Pentest
    • HTTP Connection Contamination
    • HTTP Connection Request Smuggling
    • HTTP Request Smuggling / HTTP Desync Attack
      • Browser HTTP Request Smuggling
      • Request Smuggling in HTTP/2 Downgrades
    • HTTP Response Smuggling / Desync
    • Upgrade Header Smuggling
    • hop-by-hop headers
    • IDOR
    • JWT Vulnerabilities (Json Web Tokens)
    • LDAP Injection
    • Login Bypass
      • Login bypass List
    • NoSQL injection
    • OAuth to Account takeover
    • Open Redirect
    • ORM Injection
    • Parameter Pollution
    • Phone Number Injections
    • PostMessage Vulnerabilities
      • Blocking main page to steal postmessage
      • Bypassing SOP with Iframes - 1
      • Bypassing SOP with Iframes - 2
      • Steal postmessage modifying iframe location
    • Proxy / WAF Protections Bypass
    • Race Condition
    • Rate Limit Bypass
    • Registration & Takeover Vulnerabilities
    • Regular expression Denial of Service - ReDoS
    • Reset/Forgotten Password Bypass
    • Reverse Tab Nabbing
    • SAML Attacks
      • SAML Basics
    • Server Side Inclusion/Edge Side Inclusion Injection
    • SQL Injection
      • MS Access SQL Injection
      • MSSQL Injection
      • MySQL injection
        • MySQL File priv to SSRF/RCE
      • Oracle injection
      • Cypher Injection (neo4j)
      • PostgreSQL injection
        • dblink/lo_import data exfiltration
        • PL/pgSQL Password Bruteforce
        • Network - Privesc, Port Scanner and NTLM chanllenge response disclosure
        • Big Binary Files Upload (PostgreSQL)
        • RCE with PostgreSQL Languages
        • RCE with PostgreSQL Extensions
      • SQLMap - CheatSheet
        • Second Order Injection - SQLMap
    • SSRF (Server Side Request Forgery)
      • URL Format Bypass
      • SSRF Vulnerable Platforms
      • Cloud SSRF
    • SSTI (Server Side Template Injection)
      • EL - Expression Language
      • Jinja2 SSTI
    • Timing Attacks
    • Unicode Injection
      • Unicode Normalization
    • UUID Insecurities
    • WebSocket Attacks
    • Web Tool - WFuzz
    • XPATH injection
    • XSLT Server Side Injection (Extensible Stylesheet Language Transformations)
    • XXE - XEE - XML External Entity
    • XSS (Cross Site Scripting)
      • Abusing Service Workers
      • Chrome Cache to XSS
      • Debugging Client Side JS
      • Dom Clobbering
      • DOM Invader
      • DOM XSS
      • Iframes in XSS, CSP and SOP
      • Integer Overflow
      • JS Hoisting
      • Misc JS Tricks & Relevant Info
      • PDF Injection
      • Server Side XSS (Dynamic PDF)
      • Shadow DOM
      • SOME - Same Origin Method Execution
      • Sniff Leak
      • Steal Info JS
      • XSS in Markdown
    • XSSI (Cross-Site Script Inclusion)
    • XS-Search/XS-Leaks
      • Connection Pool Examples
      • Connection Pool by Destination Example
      • Cookie Bomb + Onerror XS Leak
      • URL Max Length - Client Side
      • performance.now example
      • performance.now + Force heavy task
      • Event Loop Blocking + Lazy images
      • JavaScript Execution XS Leak
      • CSS Injection
        • CSS Injection Code
    • Iframe Traps
  • ⛈️Cloud Security
    • Pentesting Kubernetes
    • Pentesting Cloud (AWS, GCP, Az...)
    • Pentesting CI/CD (Github, Jenkins, Terraform...)
  • 😎Hardware/Physical Access
    • Physical Attacks
    • Escaping from KIOSKs
    • Firmware Analysis
      • Bootloader testing
      • Firmware Integrity
  • 🎯Binary Exploitation
    • Basic Stack Binary Exploitation Methodology
      • ELF Basic Information
      • Exploiting Tools
        • PwnTools
    • Stack Overflow
      • Pointer Redirecting
      • Ret2win
        • Ret2win - arm64
      • Stack Shellcode
        • Stack Shellcode - arm64
      • Stack Pivoting - EBP2Ret - EBP chaining
      • Uninitialized Variables
    • ROP - Return Oriented Programing
      • BROP - Blind Return Oriented Programming
      • Ret2csu
      • Ret2dlresolve
      • Ret2esp / Ret2reg
      • Ret2lib
        • Leaking libc address with ROP
          • Leaking libc - template
        • One Gadget
        • Ret2lib + Printf leak - arm64
      • Ret2syscall
        • Ret2syscall - ARM64
      • Ret2vDSO
      • SROP - Sigreturn-Oriented Programming
        • SROP - ARM64
    • Array Indexing
    • Integer Overflow
    • Format Strings
      • Format Strings - Arbitrary Read Example
      • Format Strings Template
    • Libc Heap
      • Bins & Memory Allocations
      • Heap Memory Functions
        • free
        • malloc & sysmalloc
        • unlink
        • Heap Functions Security Checks
      • Use After Free
        • First Fit
      • Double Free
      • Overwriting a freed chunk
      • Heap Overflow
      • Unlink Attack
      • Fast Bin Attack
      • Unsorted Bin Attack
      • Large Bin Attack
      • Tcache Bin Attack
      • Off by one overflow
      • House of Spirit
      • House of Lore | Small bin Attack
      • House of Einherjar
      • House of Force
      • House of Orange
      • House of Rabbit
      • House of Roman
    • Common Binary Exploitation Protections & Bypasses
      • ASLR
        • Ret2plt
        • Ret2ret & Reo2pop
      • CET & Shadow Stack
      • Libc Protections
      • Memory Tagging Extension (MTE)
      • No-exec / NX
      • PIE
        • BF Addresses in the Stack
      • Relro
      • Stack Canaries
        • BF Forked & Threaded Stack Canaries
        • Print Stack Canary
    • Write What Where 2 Exec
      • WWW2Exec - atexit()
      • WWW2Exec - .dtors & .fini_array
      • WWW2Exec - GOT/PLT
      • WWW2Exec - __malloc_hook & __free_hook
    • Common Exploiting Problems
    • Windows Exploiting (Basic Guide - OSCP lvl)
    • iOS Exploiting
  • 🔩Reversing
    • Reversing Tools & Basic Methods
      • Angr
        • Angr - Examples
      • Z3 - Satisfiability Modulo Theories (SMT)
      • Cheat Engine
      • Blobrunner
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On this page
  • Free Order Summary
  • __libc_free
  • _int_free
  • _int_free start
  • _int_free tcache
  • _int_free fast bin
  • _int_free finale
  • _int_free_merge_chunk
Edit on GitHub
  1. Binary Exploitation
  2. Libc Heap
  3. Heap Memory Functions

free

PreviousHeap Memory FunctionsNextmalloc & sysmalloc

Last updated 7 months ago

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Free Order Summary

(No checks are explained in this summary and some case have been omitted for brevity)

  1. If the address is null don't do anything

  2. If the chunk was mmaped, mummap it and finish

  3. Call _int_free:

    1. If possible, add the chunk to the tcache

    2. If possible, add the chunk to the fast bin

    3. Call _int_free_merge_chunk to consolidate the chunk is needed and add it to the unsorted list

__libc_free

Free calls __libc_free.

  • If the address passed is Null (0) don't do anything.

  • Check pointer tag

  • If the chunk is mmaped, mummap it and that all

  • If not, add the color and call _int_free over it

__lib_free code
void
__libc_free (void *mem)
{
  mstate ar_ptr;
  mchunkptr p;                          /* chunk corresponding to mem */

  if (mem == 0)                              /* free(0) has no effect */
    return;

  /* Quickly check that the freed pointer matches the tag for the memory.
     This gives a useful double-free detection.  */
  if (__glibc_unlikely (mtag_enabled))
    *(volatile char *)mem;

  int err = errno;

  p = mem2chunk (mem);

  if (chunk_is_mmapped (p))                       /* release mmapped memory. */
    {
      /* See if the dynamic brk/mmap threshold needs adjusting.
	 Dumped fake mmapped chunks do not affect the threshold.  */
      if (!mp_.no_dyn_threshold
          && chunksize_nomask (p) > mp_.mmap_threshold
          && chunksize_nomask (p) <= DEFAULT_MMAP_THRESHOLD_MAX)
        {
          mp_.mmap_threshold = chunksize (p);
          mp_.trim_threshold = 2 * mp_.mmap_threshold;
          LIBC_PROBE (memory_mallopt_free_dyn_thresholds, 2,
                      mp_.mmap_threshold, mp_.trim_threshold);
        }
      munmap_chunk (p);
    }
  else
    {
      MAYBE_INIT_TCACHE ();

      /* Mark the chunk as belonging to the library again.  */
      (void)tag_region (chunk2mem (p), memsize (p));

      ar_ptr = arena_for_chunk (p);
      _int_free (ar_ptr, p, 0);
    }

  __set_errno (err);
}
libc_hidden_def (__libc_free)

_int_free

_int_free start

It starts with some checks making sure:

  • the pointer is aligned, or trigger error free(): invalid pointer

  • the size isn't less than the minimum and that the size is also aligned or trigger error: free(): invalid size

_int_free start
// From https://github.com/bminor/glibc/blob/f942a732d37a96217ef828116ebe64a644db18d7/malloc/malloc.c#L4493C1-L4513C28

#define aligned_OK(m) (((unsigned long) (m) &MALLOC_ALIGN_MASK) == 0)

static void
_int_free (mstate av, mchunkptr p, int have_lock)
{
  INTERNAL_SIZE_T size;        /* its size */
  mfastbinptr *fb;             /* associated fastbin */

  size = chunksize (p);

  /* Little security check which won't hurt performance: the
     allocator never wraps around at the end of the address space.
     Therefore we can exclude some size values which might appear
     here by accident or by "design" from some intruder.  */
  if (__builtin_expect ((uintptr_t) p > (uintptr_t) -size, 0)
      || __builtin_expect (misaligned_chunk (p), 0))
    malloc_printerr ("free(): invalid pointer");
  /* We know that each chunk is at least MINSIZE bytes in size or a
     multiple of MALLOC_ALIGNMENT.  */
  if (__glibc_unlikely (size < MINSIZE || !aligned_OK (size)))
    malloc_printerr ("free(): invalid size");

  check_inuse_chunk(av, p);

_int_free tcache

It'll first try to allocate this chunk in the related tcache. However, some checks are performed previously. It'll loop through all the chunks of the tcache in the same index as the freed chunk and:

  • If there are more entries than mp_.tcache_count: free(): too many chunks detected in tcache

  • If the entry is not aligned: free(): unaligned chunk detected in tcache 2

  • if the freed chunk was already freed and is present as chunk in the tcache: free(): double free detected in tcache 2

If all goes well, the chunk is added to the tcache and the functions returns.

_int_free tcache
// From https://github.com/bminor/glibc/blob/f942a732d37a96217ef828116ebe64a644db18d7/malloc/malloc.c#L4515C1-L4554C7
#if USE_TCACHE
  {
    size_t tc_idx = csize2tidx (size);
    if (tcache != NULL && tc_idx < mp_.tcache_bins)
      {
	/* Check to see if it's already in the tcache.  */
	tcache_entry *e = (tcache_entry *) chunk2mem (p);

	/* This test succeeds on double free.  However, we don't 100%
	   trust it (it also matches random payload data at a 1 in
	   2^<size_t> chance), so verify it's not an unlikely
	   coincidence before aborting.  */
	if (__glibc_unlikely (e->key == tcache_key))
	  {
	    tcache_entry *tmp;
	    size_t cnt = 0;
	    LIBC_PROBE (memory_tcache_double_free, 2, e, tc_idx);
	    for (tmp = tcache->entries[tc_idx];
		 tmp;
		 tmp = REVEAL_PTR (tmp->next), ++cnt)
	      {
		if (cnt >= mp_.tcache_count)
		  malloc_printerr ("free(): too many chunks detected in tcache");
		if (__glibc_unlikely (!aligned_OK (tmp)))
		  malloc_printerr ("free(): unaligned chunk detected in tcache 2");
		if (tmp == e)
		  malloc_printerr ("free(): double free detected in tcache 2");
		/* If we get here, it was a coincidence.  We've wasted a
		   few cycles, but don't abort.  */
	      }
	  }

	if (tcache->counts[tc_idx] < mp_.tcache_count)
	  {
	    tcache_put (p, tc_idx);
	    return;
	  }
      }
  }
#endif

_int_free fast bin

Start by checking that the size is suitable for fast bin and check if it's possible to set it close to the top chunk.

Then, add the freed chunk at the top of the fast bin while performing some checks:

  • If the size of the chunk is invalid (too big or small) trigger: free(): invalid next size (fast)

  • If the added chunk was already the top of the fast bin: double free or corruption (fasttop)

  • If the size of the chunk at the top has a different size of the chunk we are adding: invalid fastbin entry (free)

_int_free Fast Bin
 // From https://github.com/bminor/glibc/blob/f942a732d37a96217ef828116ebe64a644db18d7/malloc/malloc.c#L4556C2-L4631C4
 
 /*
    If eligible, place chunk on a fastbin so it can be found
    and used quickly in malloc.
  */

  if ((unsigned long)(size) <= (unsigned long)(get_max_fast ())

#if TRIM_FASTBINS
      /*
	If TRIM_FASTBINS set, don't place chunks
	bordering top into fastbins
      */
      && (chunk_at_offset(p, size) != av->top)
#endif
      ) {

    if (__builtin_expect (chunksize_nomask (chunk_at_offset (p, size))
			  <= CHUNK_HDR_SZ, 0)
	|| __builtin_expect (chunksize (chunk_at_offset (p, size))
			     >= av->system_mem, 0))
      {
	bool fail = true;
	/* We might not have a lock at this point and concurrent modifications
	   of system_mem might result in a false positive.  Redo the test after
	   getting the lock.  */
	if (!have_lock)
	  {
	    __libc_lock_lock (av->mutex);
	    fail = (chunksize_nomask (chunk_at_offset (p, size)) <= CHUNK_HDR_SZ
		    || chunksize (chunk_at_offset (p, size)) >= av->system_mem);
	    __libc_lock_unlock (av->mutex);
	  }

	if (fail)
	  malloc_printerr ("free(): invalid next size (fast)");
      }

    free_perturb (chunk2mem(p), size - CHUNK_HDR_SZ);

    atomic_store_relaxed (&av->have_fastchunks, true);
    unsigned int idx = fastbin_index(size);
    fb = &fastbin (av, idx);

    /* Atomically link P to its fastbin: P->FD = *FB; *FB = P;  */
    mchunkptr old = *fb, old2;

    if (SINGLE_THREAD_P)
      {
	/* Check that the top of the bin is not the record we are going to
	   add (i.e., double free).  */
	if (__builtin_expect (old == p, 0))
	  malloc_printerr ("double free or corruption (fasttop)");
	p->fd = PROTECT_PTR (&p->fd, old);
	*fb = p;
      }
    else
      do
	{
	  /* Check that the top of the bin is not the record we are going to
	     add (i.e., double free).  */
	  if (__builtin_expect (old == p, 0))
	    malloc_printerr ("double free or corruption (fasttop)");
	  old2 = old;
	  p->fd = PROTECT_PTR (&p->fd, old);
	}
      while ((old = catomic_compare_and_exchange_val_rel (fb, p, old2))
	     != old2);

    /* Check that size of fastbin chunk at the top is the same as
       size of the chunk that we are adding.  We can dereference OLD
       only if we have the lock, otherwise it might have already been
       allocated again.  */
    if (have_lock && old != NULL
	&& __builtin_expect (fastbin_index (chunksize (old)) != idx, 0))
      malloc_printerr ("invalid fastbin entry (free)");
  }

_int_free finale

If the chunk wasn't allocated yet on any bin, call _int_free_merge_chunk

_int_free finale
/*
    Consolidate other non-mmapped chunks as they arrive.
  */

  else if (!chunk_is_mmapped(p)) {

    /* If we're single-threaded, don't lock the arena.  */
    if (SINGLE_THREAD_P)
      have_lock = true;

    if (!have_lock)
      __libc_lock_lock (av->mutex);

    _int_free_merge_chunk (av, p, size);

    if (!have_lock)
      __libc_lock_unlock (av->mutex);
  }
  /*
    If the chunk was allocated via mmap, release via munmap().
  */

  else {
    munmap_chunk (p);
  }
}

_int_free_merge_chunk

This function will try to merge chunk P of SIZE bytes with its neighbours. Put the resulting chunk on the unsorted bin list.

Some checks are performed:

  • If the chunk is the top chunk: double free or corruption (top)

  • If the next chunk is outside of the boundaries of the arena: double free or corruption (out)

  • If the chunk is not marked as used (in the prev_inuse from the following chunk): double free or corruption (!prev)

  • If the next chunk has a too little size or too big: free(): invalid next size (normal)

  • if the previous chunk is not in use, it will try to consolidate. But, if the prev_size differs from the size indicated in the previous chunk: corrupted size vs. prev_size while consolidating

_int_free_merge_chunk code
// From https://github.com/bminor/glibc/blob/f942a732d37a96217ef828116ebe64a644db18d7/malloc/malloc.c#L4660C1-L4702C2

/* Try to merge chunk P of SIZE bytes with its neighbors.  Put the
   resulting chunk on the appropriate bin list.  P must not be on a
   bin list yet, and it can be in use.  */
static void
_int_free_merge_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T size)
{
  mchunkptr nextchunk = chunk_at_offset(p, size);

  /* Lightweight tests: check whether the block is already the
     top block.  */
  if (__glibc_unlikely (p == av->top))
    malloc_printerr ("double free or corruption (top)");
  /* Or whether the next chunk is beyond the boundaries of the arena.  */
  if (__builtin_expect (contiguous (av)
			&& (char *) nextchunk
			>= ((char *) av->top + chunksize(av->top)), 0))
    malloc_printerr ("double free or corruption (out)");
  /* Or whether the block is actually not marked used.  */
  if (__glibc_unlikely (!prev_inuse(nextchunk)))
    malloc_printerr ("double free or corruption (!prev)");

  INTERNAL_SIZE_T nextsize = chunksize(nextchunk);
  if (__builtin_expect (chunksize_nomask (nextchunk) <= CHUNK_HDR_SZ, 0)
      || __builtin_expect (nextsize >= av->system_mem, 0))
    malloc_printerr ("free(): invalid next size (normal)");

  free_perturb (chunk2mem(p), size - CHUNK_HDR_SZ);

  /* Consolidate backward.  */
  if (!prev_inuse(p))
    {
      INTERNAL_SIZE_T prevsize = prev_size (p);
      size += prevsize;
      p = chunk_at_offset(p, -((long) prevsize));
      if (__glibc_unlikely (chunksize(p) != prevsize))
        malloc_printerr ("corrupted size vs. prev_size while consolidating");
      unlink_chunk (av, p);
    }

  /* Write the chunk header, maybe after merging with the following chunk.  */
  size = _int_free_create_chunk (av, p, size, nextchunk, nextsize);
  _int_free_maybe_consolidate (av, size);
}
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