A **Use-After-Free (UAF) vulnerability (CVE-2019-5786)** was discovered in **Google Chrome’s FileReader API**, exposing millions of users to remote code execution (RCE) risks. The flaw arose when JavaScript triggered the destruction of `FileReader` objects while asynchronous file operations were still pending, creating a window for attackers to manipulate freed memory during callback execution. Exploiting this, adversaries could craft malicious web pages to corrupt memory, bypass Chrome’s sandbox protections, and execute arbitrary code within the browser’s renderer process.The vulnerability was particularly severe due to Chrome’s widespread use and the complexity of its JavaScript engine, which manages intricate object lifecycles. Attackers leveraged **heap spraying** and **type confusion** techniques to overwrite critical data structures, enabling full system compromise on unpatched devices. While Google patched the issue in an emergency update (Chrome 72.0.3626.121), the exploit demonstrated how UAF vulnerabilities in memory-unsafe languages (C/C++) remain a persistent threat, even in modern, sandboxed applications. The incident underscored the need for stricter memory safety mechanisms, such as **AddressSanitizer (ASan)** in development and **Control Flow Integrity (CFI)** in production.
Source: https://cybersecuritynews.com/use-after-free-vulnerability/
TPRM report: https://www.rankiteo.com/company/google
"id": "goo407081825",
"linkid": "google",
"type": "Vulnerability",
"date": "6/2019",
"severity": "100",
"impact": "",
"explanation": "Attack threatening the organization’s existence"{'affected_entities': [{'customers_affected': 'Millions (All Chrome Users '
'Pre-Patch)',
'industry': 'Technology',
'location': 'Global',
'name': 'Google Chrome (CVE-2019-5786)',
'size': 'Large-Scale (Millions of Users)',
'type': 'Web Browser'},
{'industry': 'Multiple (Tech, Critical Infrastructure, '
'Embedded Systems)',
'location': 'Global',
'name': 'Applications Using C/C++ with Manual Memory '
'Management',
'type': 'Software'}],
'attack_vector': ['Memory Allocator Manipulation',
'Heap Spraying',
'Dangling Pointer Dereference',
'Function Pointer Overwrite',
'Virtual Function Table Corruption',
'Race Conditions in Multithreaded Code',
'Callback-Based Object Lifetime Exploitation',
'JavaScript Engine Manipulation (e.g., Chrome FileReader)',
'Pointer Authentication Bypass'],
'customer_advisories': ['Update software (e.g., browsers, OS) to the latest '
'versions to mitigate known UAF vulnerabilities.',
'Avoid untrusted websites/plugins that may trigger '
'UAF exploits (e.g., malicious JavaScript).',
'Enable exploit mitigations (e.g., Windows DEP/ASLR, '
'macOS SIP).',
'Report unexpected crashes (potential UAF triggers) '
'to vendors.'],
'data_breach': {'data_exfiltration': ['Possible via Crafted Exploits (e.g., '
'Reading Freed Memory)'],
'personally_identifiable_information': ['Potential (If PII '
'Resided in Freed '
'Memory)'],
'sensitivity_of_data': ['High (If Exploited to Leak Secrets '
'from Memory)',
'Variable (Depends on Target '
'Application)'],
'type_of_data_compromised': ['Potential Memory Contents '
'(Depends on Exploitation)',
'Sensitive Data in Freed Blocks '
'(e.g., Credentials, Tokens)']},
'description': 'Use-after-free (UAF) vulnerabilities occur when a program '
'continues to use a memory location after it has been freed, '
'enabling attackers to manipulate program execution, corrupt '
'data, or achieve arbitrary code execution. These '
'vulnerabilities are prevalent in applications written in '
'memory-unsafe languages like C and C++. They arise from '
'flawed memory management practices, such as failing to '
'nullify pointers after freeing memory or improper handling of '
'object lifetimes. Exploitation often involves heap spraying, '
'memory layout control, and advanced techniques like '
'Return-Oriented Programming (ROP) to bypass mitigations like '
'DEP and ASLR. High-profile cases include CVE-2019-5786 in '
'Google Chrome, which allowed arbitrary code execution in the '
'browser’s renderer process via JavaScript manipulation of '
'FileReader objects. Mitigation requires a multi-layered '
'approach, including static/dynamic analysis, memory-safe '
'languages (e.g., Rust), runtime protections (e.g., ASan, '
'CFI), and secure coding practices like pointer nullification '
'and reference counting.',
'impact': {'brand_reputation_impact': ['Erosion of Trust in Affected Software '
'(e.g., Browsers, OS)',
'Negative Publicity for Vulnerable '
'Products'],
'data_compromised': ['Potential Memory Leakage (Sensitive Data in '
'Freed Blocks)',
'Corruption of Application State'],
'downtime': ['Application Crashes (e.g., ASan-Triggered '
'Termination)',
'Denial-of-Service via Memory Corruption'],
'identity_theft_risk': ['If Exploited to Leak PII from Memory'],
'operational_impact': ['Unpredictable Program Behavior',
'Exploitation for Further Attacks (e.g., '
'ROP Chains)',
'Bypass of Security Sandboxes (e.g., '
'Browser Renderer Process)'],
'payment_information_risk': ['If Exploited to Leak Payment Data '
'from Memory (e.g., Browser '
'Sessions)'],
'systems_affected': ['Web Browsers (e.g., Google Chrome)',
'Operating Systems (Kernel/Userspace '
'Components)',
'Critical Infrastructure Software',
'Applications Written in C/C++',
'JavaScript Engines (e.g., V8)',
'DOM Manipulation Libraries']},
'initial_access_broker': {'backdoors_established': ['Persistent UAF '
'Conditions in '
'Long-Running Processes '
'(e.g., Daemons)',
'Corrupted Function '
'Pointers for Later '
'Exploitation'],
'data_sold_on_dark_web': ['Exploit Kits for UAF '
'Vulnerabilities (e.g., '
'Browser Exploits)',
'Proof-of-Concept (PoC) '
'Code for Zero-Days'],
'entry_point': ['Memory Corruption via Crafted '
'Input (e.g., Malicious File, '
'Network Packet)',
'Race Conditions in Object '
'Destruction (e.g., Chrome '
'FileReader)',
'Heap Manipulation via Allocator '
'Predictability'],
'high_value_targets': ['Browser Renderer Processes '
'(Sandbox Escape)',
'OS Kernel Memory (Privilege '
'Escalation)',
'Critical Infrastructure '
'Control Systems (Lateral '
'Movement)'],
'reconnaissance_period': ['Analysis of Target '
'Allocator Behavior '
'(e.g., Heap Spraying '
'Setup)',
'Probing for UAF-Triggers '
'(e.g., Fuzzing for '
'Crashes)']},
'investigation_status': 'Ongoing (General Class of Vulnerability; Specific '
'Instances May Vary)',
'lessons_learned': ['Memory-unsafe languages (C/C++) remain a primary attack '
'surface for high-severity vulnerabilities like UAF.',
'Complex software (e.g., browsers, OS kernels) with '
'intricate object lifecycles are particularly vulnerable '
'to UAF due to race conditions and callback-heavy '
'architectures.',
'Exploitation techniques evolve rapidly, with attackers '
'leveraging hardware features (e.g., pointer '
'authentication) and bypassing mitigations (e.g., DEP, '
'ASLR).',
'Static and dynamic analysis tools (ASan, Valgrind) are '
'critical for detecting UAF but introduce performance '
'overhead, limiting their use in production.',
'Transitioning to memory-safe languages (Rust, Go) or '
'managed runtimes (Java, C#) is the most effective '
'long-term mitigation.',
'Runtime protections (CFI, hardware-assisted sanitizers) '
'provide defense-in-depth but are not foolproof against '
'sophisticated exploits.',
'Secure coding practices (pointer nullification, RAII, '
'reference counting) must be enforced rigorously in '
'legacy codebases.',
'Heap spraying and memory layout control remain '
'foundational to UAF exploitation, highlighting the need '
'for allocator hardening (e.g., Scudo, PartitionAlloc).',
'Public disclosure of UAF vulnerabilities (e.g., '
'CVE-2019-5786) drives awareness but also provides '
'attackers with exploitation blueprints, necessitating '
'rapid patching.'],
'motivation': ['Arbitrary Code Execution',
'Privilege Escalation',
'Data Corruption',
'Bypassing Security Mitigations (DEP, ASLR, CFI)',
'Exploit Development for Malware Distribution',
'Targeted Attacks on Browsers/OS/Critical Infrastructure'],
'post_incident_analysis': {'corrective_actions': ['Mandate Static Analysis '
'(ASan, Clang) for All '
'C/C++ Code',
'Refactor Critical '
'Components to Use Smart '
'Pointers (e.g., '
'`std::shared_ptr`)',
'Implement Custom '
'Allocators with UAF '
'Detection (e.g., Guard '
'Pages)',
'Enforce Code Reviews '
'Focused on Memory Safety',
'Deploy Runtime Mitigations '
'(CFI, Hardware-Based '
'Protections)',
'Establish a Bug Bounty '
'Program for UAF Reports '
'(e.g., Chrome VRP)',
'Document Object Lifetime '
'Rules for Complex Systems '
'(e.g., Browsers)',
'Train Developers on UAF '
'Exploitation Techniques to '
'Raise Awareness'],
'root_causes': ['Lack of Pointer Nullification '
'After Free',
'Ambiguous Object Ownership in '
'Complex Codebases',
'Race Conditions in Asynchronous '
'Operations (e.g., Callbacks)',
'Overreliance on Manual Memory '
'Management in C/C++',
'Insufficient Static/Dynamic '
'Analysis Coverage',
'Heap Allocator Designs Prone to '
'Predictable Layouts',
'Inadequate Sandboxing for '
'Memory-Unsafe Components']},
'recommendations': [{'category': 'Prevention',
'measures': ['Adopt memory-safe languages (Rust, Swift) '
'for new projects or critical components.',
'Migrate legacy C/C++ codebases to managed '
'languages (Java, C#) where feasible.',
'Implement static analysis (Clang Static '
'Analyzer, PVS-Studio) in CI/CD pipelines.',
'Use dynamic analysis tools (ASan, '
'Valgrind) during testing, despite '
'performance costs.',
'Enforce secure coding standards for memory '
'management (e.g., MISRA C, CERT C).',
'Design clear object ownership models '
'(RAII) and avoid raw pointers where '
'possible.']},
{'category': 'Detection',
'measures': ['Deploy hardened allocators (Scudo, '
'PartitionAlloc) in production for runtime '
'UAF detection.',
'Enable AddressSanitizer (ASan) in debug '
'builds and fuzz testing.',
'Use Control Flow Integrity (CFI) to detect '
'exploitation attempts.',
'Monitor for unusual memory access patterns '
'(e.g., via eBPF-based tools).',
'Implement canaries or guards for critical '
'objects prone to UAF.']},
{'category': 'Mitigation',
'measures': ['Apply compiler mitigations (e.g., '
'`-fstack-protector`, '
'`-D_FORTIFY_SOURCE=2`).',
'Enable hardware protections (Intel CET, '
'ARM Pointer Authentication).',
'Isolate high-risk components (e.g., '
'browser renderer processes in sandboxes).',
'Use probabilistic defenses (e.g., ASLR, '
'heap randomization) to raise exploitation '
'difficulty.',
'Deploy exploit mitigation frameworks '
'(e.g., Microsoft EMET, Linux seccomp).']},
{'category': 'Response',
'measures': ['Establish incident response plans '
'specifically for memory corruption '
'vulnerabilities.',
'Coordinate with security researchers for '
'responsible disclosure (e.g., Chrome VRP).',
'Prioritize patching based on '
'exploitability (e.g., UAF in '
'network-facing code).',
'Communicate transparently with users about '
'risks and mitigations (e.g., Chrome '
'release notes).',
'Conduct post-incident root cause analysis '
'to identify systemic issues (e.g., flawed '
'object lifetimes).']},
{'category': 'Long-Term Strategy',
'measures': ['Invest in rewriting critical components in '
'memory-safe languages.',
'Fund research into automated UAF detection '
'(e.g., ML-based static analysis).',
'Advocate for industry-wide adoption of '
'memory safety (e.g., Rust in Linux '
'kernel).',
'Collaborate with hardware vendors to '
'improve exploit mitigation (e.g., ARM '
'MTE).',
'Train developers on secure memory '
'management and exploitation techniques.']}],
'references': [{'source': 'Google Chrome Security Advisory for CVE-2019-5786',
'url': 'https://chromereleases.googleblog.com/2019/03/stable-channel-update-for-desktop.html'},
{'source': 'AddressSanitizer (ASan) Documentation',
'url': 'https://github.com/google/sanitizers/wiki/AddressSanitizer'},
{'source': 'Valgrind Memcheck Manual',
'url': 'https://valgrind.org/docs/manual/mc-manual.html'},
{'source': 'Rust Programming Language (Memory Safety)',
'url': 'https://www.rust-lang.org/'},
{'source': 'CERT C Coding Standard (MEM00-CPP, MEM30-C)',
'url': 'https://wiki.sei.cmu.edu/confluence/display/c/SEI+CERT+C+Coding+Standard'},
{'source': 'Intel Control-flow Enforcement Technology (CET)',
'url': 'https://www.intel.com/content/www/us/en/developer/articles/technical/control-flow-enforcement-technology.html'},
{'source': 'ARM Memory Tagging Extension (MTE)',
'url': 'https://developer.arm.com/Architectures/Memory%20Tagging%20Extension'},
{'source': 'Scudo Hardened Allocator',
'url': 'https://llvm.org/docs/ScudoHardenedAllocator.html'}],
'response': {'communication_strategy': ['Security Advisories (e.g., Chrome '
'Releases Blog)',
'CVE Publications (e.g., '
'CVE-2019-5786)',
'Developer Guidance on Secure Coding '
'Practices'],
'containment_measures': ['Patching Vulnerable Code (e.g., Chrome '
'Updates)',
'Disabling Affected Features (e.g., '
'FileReader API Workarounds)',
'Isolating Vulnerable Components (e.g., '
'Sandboxing)'],
'enhanced_monitoring': ['Runtime UAF Detection (e.g., ASan in '
'Debug Builds)',
'Heap Integrity Checks in Production'],
'recovery_measures': ['Rollback to Stable Versions (if Exploited '
'in Production)',
'Memory State Validation for Critical '
'Objects'],
'remediation_measures': ['Code Refactoring to Eliminate UAF '
'Conditions',
'Adoption of Memory-Safe Languages '
'(e.g., Rust for New Components)',
'Integration of Static/Dynamic Analysis '
'Tools (ASan, Valgrind)',
'Pointer Nullification Post-Free',
'Reference Counting for Shared Objects'],
'third_party_assistance': ['Security Researchers (e.g., '
'CVE-2019-5786 Disclosure)',
'Compiler/Toolchain Developers (e.g., '
'ASan, Clang)']},
'stakeholder_advisories': ['Developers: Adopt memory-safe languages and '
'static analysis tools.',
'Security Teams: Monitor for UAF exploitation '
'attempts (e.g., heap spraying).',
'Executives: Allocate resources for long-term '
'migration away from C/C++.',
'End Users: Apply patches promptly (e.g., browser '
'updates).'],
'title': 'Use-After-Free (UAF) Vulnerabilities in Memory-Unsafe Languages '
'(C/C++)',
'type': ['Memory Corruption Vulnerability',
'Use-After-Free (UAF)',
'Arbitrary Code Execution',
'Type Confusion'],
'vulnerability_exploited': ['Use-After-Free (UAF)',
'Improper Pointer Nullification',
'Race Conditions in Object Destruction',
'Type Confusion via Memory Reuse',
'Heap Metadata Corruption',
'CVE-2019-5786 (Google Chrome FileReader)']}