CVE-2022-37454: Keccak XKCP Buffer Overflow Vulnerability

CVE-2022-37454 Overview

CVE-2022-37454 is a critical integer overflow vulnerability in the Keccak XKCP SHA-3 reference implementation that leads to a resultant buffer overflow. This vulnerability occurs within the sponge function interface and allows attackers to execute arbitrary code or eliminate expected cryptographic properties. The flaw affects the foundational cryptographic library used by numerous programming languages and platforms, including Python, PHP, and PyPy, making it a high-impact vulnerability with widespread implications.

The vulnerability stems from improper handling of integer values during cryptographic operations, where an overflow condition can be triggered to corrupt memory and potentially achieve code execution. Given that SHA-3 is a widely adopted cryptographic hash function standardized by NIST, this vulnerability poses significant risks to applications relying on SHA-3 for security-critical operations such as digital signatures, message authentication, and data integrity verification.

Critical Impact

Attackers can exploit this integer overflow to execute arbitrary code or compromise cryptographic guarantees, potentially undermining the security of systems relying on SHA-3 hash functions for authentication, integrity, and encryption operations.

Affected Products

• Extended Keccak Code Package (XKCP) - versions before commit fdc6fef
• PHP - multiple versions implementing SHA-3
• Python - multiple versions with hashlib SHA-3 support
• PyPy - multiple versions
• PySHA3 project
• SHA3 Ruby gem
• Debian Linux 10.0 and 11.0
• Fedora 35 and 36

Discovery Timeline

• 2022-10-21 - CVE-2022-37454 published to NVD
• 2025-05-08 - Last updated in NVD database

Technical Details for CVE-2022-37454

Vulnerability Analysis

This vulnerability represents a classic integer overflow leading to a buffer overflow condition in cryptographic code. The flaw exists in the sponge function interface of the Keccak reference implementation, which is the core construction underlying the SHA-3 family of hash functions. When processing specially crafted input data, the implementation fails to properly validate size calculations, allowing an integer to wrap around and produce an unexpectedly small buffer allocation or incorrect boundary checks.

The sponge construction is fundamental to SHA-3's design, absorbing input data in blocks and squeezing out the hash output. The vulnerability allows attackers to manipulate this process by providing input that triggers the integer overflow during size calculations, subsequently causing the buffer overflow when data is written beyond allocated memory boundaries.

This flaw is particularly concerning because it affects a reference implementation that has been adopted or copied by numerous downstream projects. The cryptographic nature of the affected code means that exploitation could not only achieve code execution but also undermine the mathematical security guarantees that applications depend on for protecting sensitive data.

Root Cause

The root cause is an integer overflow vulnerability (CWE-190) in the size calculations within the sponge function interface. When processing input data, the implementation performs arithmetic operations on size values without adequate overflow checks. When sufficiently large input sizes are provided, these calculations overflow, resulting in:

1. Incorrect buffer size allocations - The overflowed value may result in allocating a smaller buffer than required
2. Bypassed boundary checks - Size comparisons may pass when they should fail due to the wrapped integer value
3. Out-of-bounds memory writes - Data is subsequently written beyond the allocated buffer boundaries

The vulnerability was addressed in commit fdc6fef of the XKCP repository, which introduced proper bounds checking and integer overflow prevention mechanisms.

Attack Vector

The attack vector is network-accessible, requiring no privileges or user interaction. An attacker can exploit this vulnerability by:

1. Providing malicious input - Crafting input data with specific size values designed to trigger the integer overflow
2. Triggering the sponge function - Having the application process this input through SHA-3 hash operations
3. Exploiting the buffer overflow - Leveraging the resulting memory corruption to achieve code execution or corrupt cryptographic state

The vulnerability can be exploited through any application interface that accepts user-controlled data for SHA-3 hashing operations. This includes web applications processing file uploads, network services performing authentication, and any system using SHA-3 for data integrity verification.

Due to the nature of the vulnerability, exploitation could manifest in two primary ways: achieving arbitrary code execution through controlled memory corruption, or silently compromising the cryptographic properties of the hash function without visible errors. The latter is particularly insidious as it could undermine security without triggering obvious failures.

Detection Methods for CVE-2022-37454

Indicators of Compromise

• Abnormal crashes or segmentation faults in applications using SHA-3 hash functions
• Unexpected memory corruption errors in cryptographic libraries or their dependencies
• Application logs showing hash operation failures with unusually large input sizes
• Memory analysis revealing heap corruption patterns near SHA-3 library allocations

Detection Strategies

• Monitor for anomalous input sizes being passed to SHA-3 hashing functions in application logs
• Implement runtime application self-protection (RASP) to detect integer overflow conditions in cryptographic operations
• Deploy memory safety tools such as AddressSanitizer during development and testing phases
• Use SentinelOne's behavioral AI to detect exploitation attempts targeting cryptographic libraries

Monitoring Recommendations

• Enable detailed logging for applications processing external input through cryptographic hash functions
• Configure intrusion detection systems to alert on patterns associated with buffer overflow exploitation
• Implement application performance monitoring to detect unusual memory allocation patterns
• Review system logs for crash reports associated with Python, PHP, or other affected runtime environments

How to Mitigate CVE-2022-37454

Immediate Actions Required

• Update the Keccak XKCP library to a version containing commit fdc6fef or later
• Upgrade PHP to patched versions that address this vulnerability
• Upgrade Python installations to patched versions with corrected hashlib implementations
• Update PyPy, Pysha3, and SHA3 Ruby gem to their respective patched versions
• Apply operating system security updates for Debian and Fedora systems

Patch Information

The vulnerability has been addressed through patches released by the XKCP project and downstream maintainers. The primary fix is contained in XKCP commit fdc6fef, which implements proper integer overflow checks in the sponge function interface. Major distributions and language runtimes have incorporated this fix:

• XKCP: Fixed in commit fdc6fef - see GitHub Security Advisory GHSA-6w4m-2xhg-2658
• Debian: Security advisories DSA-5267 and DSA-5269 provide patched packages
• Fedora: Updated packages available through standard update channels
• Gentoo: GLSA 2023-05-02 provides guidance for affected systems

Organizations should prioritize updating all affected components, particularly in systems that process untrusted input through SHA-3 operations.

Workarounds

• Implement input size validation before passing data to SHA-3 functions to reject abnormally large inputs
• Consider using alternative hash functions (SHA-256, SHA-512) temporarily if SHA-3 patching cannot be performed immediately
• Deploy web application firewalls configured to limit input sizes to cryptographic endpoints
• Isolate applications using vulnerable SHA-3 implementations in sandboxed environments to limit exploitation impact

# Example: Check Python version for vulnerable hashlib
python3 --version
python3 -c "import hashlib; print('SHA3 available:', 'sha3_256' in hashlib.algorithms_available)"

# Update Python packages on Debian/Ubuntu
sudo apt update && sudo apt upgrade python3

# Update PHP on Debian/Ubuntu
sudo apt update && sudo apt upgrade php

# Check for XKCP library version
# Verify your installation includes commit fdc6fef or later