CVE-2022-24963: Apache Portable Runtime Buffer Overflow

CVE-2022-24963 Overview

CVE-2022-24963 is an Integer Overflow vulnerability affecting the apr_encode functions within the Apache Portable Runtime (APR) library. This vulnerability enables an attacker to trigger an integer overflow or wraparound condition, which subsequently allows writing data beyond the bounds of an allocated buffer. The Apache Portable Runtime is a widely used support library that provides a portable interface to underlying platform-specific implementations, making this vulnerability particularly impactful across numerous applications and systems that depend on APR.

Critical Impact

This integer overflow vulnerability can lead to out-of-bounds memory writes, potentially enabling remote code execution, denial of service, or complete system compromise on systems running affected versions of Apache Portable Runtime.

Affected Products

• Apache Portable Runtime (APR) version 1.7.0
• Applications and services built on APR 1.7.0
• Web servers and infrastructure components utilizing the vulnerable APR library

Discovery Timeline

• 2023-01-31 - CVE-2022-24963 published to NVD
• 2025-03-27 - Last updated in NVD database

Technical Details for CVE-2022-24963

Vulnerability Analysis

The vulnerability resides in the apr_encode family of functions within the Apache Portable Runtime library. These functions are responsible for encoding data into various formats, a common operation in web applications and network services. The core issue is an integer overflow that occurs during buffer size calculations.

When processing input data, the affected functions calculate the required buffer size for storing encoded output. However, due to improper handling of integer arithmetic, specially crafted input can cause the size calculation to overflow, wrapping around to a much smaller value than required. This results in an undersized buffer being allocated, and subsequent write operations exceed the buffer boundaries.

The network-accessible nature of this vulnerability, combined with no authentication requirements and low attack complexity, makes it particularly dangerous. An attacker can exploit this vulnerability remotely without any user interaction, potentially achieving arbitrary code execution, data corruption, or causing denial of service conditions.

Root Cause

The root cause is classified as CWE-190 (Integer Overflow or Wraparound). The apr_encode functions fail to properly validate input sizes before performing arithmetic operations for buffer allocation. When input lengths approach maximum integer values, the multiplication or addition operations used in size calculations can overflow, resulting in a value that wraps around to a small positive number. This undersized allocation then leads to heap buffer overflows when the encoding operations write beyond the allocated memory region.

Attack Vector

The attack vector is network-based, allowing remote exploitation. An attacker can submit maliciously crafted input data to any network-accessible service that processes data through the vulnerable apr_encode functions. The attack requires no privileges or authentication, and no user interaction is needed for successful exploitation.

The exploitation flow involves sending oversized or specially calculated input values that trigger the integer overflow during buffer size computation. When the encoding function allocates an insufficient buffer based on the wrapped calculation, the actual encoding operation writes past the buffer boundary, enabling memory corruption. Depending on the memory layout and application context, this could allow an attacker to overwrite critical data structures, function pointers, or inject executable code.

Detection Methods for CVE-2022-24963

Indicators of Compromise

• Unexpected application crashes or segmentation faults in services using APR library
• Abnormal memory consumption patterns in APR-dependent applications
• Log entries indicating buffer-related errors in apr_encode function calls
• Unusual network traffic patterns targeting APR-dependent services with oversized or malformed data

Detection Strategies

• Implement runtime application self-protection (RASP) to detect buffer overflow attempts
• Deploy network intrusion detection systems (NIDS) with signatures for anomalous data patterns targeting APR services
• Enable address sanitizer (ASan) in development and testing environments to identify memory corruption
• Monitor system logs for crash dumps and core files from APR-dependent applications

Monitoring Recommendations

• Establish baseline metrics for APR-dependent application memory usage and alert on deviations
• Configure centralized logging to capture and correlate error events from all APR-utilizing services
• Implement file integrity monitoring on APR library files to detect unauthorized modifications
• Deploy endpoint detection and response (EDR) solutions to identify post-exploitation behavior

How to Mitigate CVE-2022-24963

Immediate Actions Required

• Inventory all systems and applications using Apache Portable Runtime library
• Update Apache Portable Runtime to a patched version that addresses the integer overflow
• Implement input validation and size limits at the application layer as a defense-in-depth measure
• Consider temporarily disabling or restricting access to services using the vulnerable APR version until patching is complete

Patch Information

Organizations should update to a patched version of Apache Portable Runtime that addresses this vulnerability. Refer to the Apache Mailing List Thread for official vendor guidance and patch availability. Additional context is available in the NetApp Security Advisory NTAP-20230908-0008 for NetApp products affected by this vulnerability.

Workarounds

• Implement Web Application Firewall (WAF) rules to filter requests with abnormally large input sizes
• Apply network segmentation to limit exposure of APR-dependent services to trusted networks
• Enable operating system-level memory protections such as ASLR and DEP/NX bit
• Consider deploying SentinelOne Singularity platform for real-time protection against exploitation attempts targeting this vulnerability

# Configuration example - Verify APR version and plan upgrade
# Check installed APR version
apr-1-config --version

# Review dependent services
ldd /path/to/application | grep apr

# After upgrading, verify the new version
apr-1-config --version