CVE-2022-23772: Golang Go DOS Vulnerability

CVE-2022-23772 Overview

CVE-2022-23772 is an integer overflow vulnerability in the Rat.SetString function within the math/big package of Go programming language. This flaw affects Go versions before 1.16.14 and 1.17.x before 1.17.7, allowing attackers to trigger uncontrolled memory consumption through specially crafted input. The vulnerability resides in the rational number parsing logic, where improper handling of large exponents can cause the application to allocate excessive memory, leading to denial of service conditions.

Critical Impact

Remote attackers can exploit this vulnerability over the network without authentication to cause denial of service through memory exhaustion in any Go application using the math/big package to parse untrusted rational number input.

Affected Products

• Golang Go (versions before 1.16.14 and 1.17.x before 1.17.7)
• NetApp BeeGFS CSI Driver
• NetApp Cloud Insights Telegraf Agent
• NetApp Kubernetes Monitoring Operator
• NetApp StorageGRID
• Debian Linux 9.0

Discovery Timeline

• 2022-02-11 - CVE-2022-23772 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-23772

Vulnerability Analysis

The vulnerability exists in Go's math/big package, specifically within the Rat.SetString function used for parsing rational numbers from string representations. When processing rational number strings with extremely large exponent values, the function fails to properly validate the exponent bounds before performing memory allocation operations.

The math/big package provides arbitrary-precision arithmetic in Go and is commonly used in cryptographic operations, financial calculations, and scientific computing applications. The Rat type represents rational numbers as a ratio of two arbitrary-precision integers. The SetString method parses a string representation of a rational number and sets the receiver to that value.

The root issue is an integer overflow in the exponent handling logic. When a malicious input contains an extremely large exponent value, the overflow causes the allocation size calculation to produce an unexpectedly large value, resulting in massive memory allocation attempts that can exhaust system resources.

Root Cause

The vulnerability is classified as CWE-190 (Integer Overflow or Wraparound). The Rat.SetString function does not adequately validate the magnitude of the exponent component in rational number strings before using it in memory allocation calculations. When processing strings with extremely large exponents (e.g., "1e999999999999999999"), the internal calculations overflow, leading to attempts to allocate enormous amounts of memory.

The lack of proper bounds checking on the exponent value allows attackers to specify arbitrary exponent sizes that exceed reasonable computational limits, triggering the overflow condition and subsequent memory exhaustion.

Attack Vector

This vulnerability can be exploited remotely over the network without requiring authentication or user interaction. An attacker needs to send a specially crafted string to any Go application that uses Rat.SetString to parse user-supplied input.

The attack is particularly dangerous in scenarios such as:

• Web applications accepting numeric input that gets parsed as rational numbers
• API endpoints processing JSON or other data formats containing large numbers
• Configuration parsers that read external configuration files
• Any service that processes mathematical expressions from untrusted sources

The vulnerability mechanism involves passing a maliciously crafted string with an extremely large exponent value to the Rat.SetString function. When the function attempts to process this input, the integer overflow in exponent handling causes allocation of excessive memory, potentially crashing the application or degrading system performance. For detailed technical analysis, refer to the Golang Announcement.

Detection Methods for CVE-2022-23772

Indicators of Compromise

• Unusual memory consumption spikes in Go applications
• Application crashes with out-of-memory errors
• Log entries showing allocation failures in processes using math/big package
• Network requests containing extremely large numeric strings with high exponent values

Detection Strategies

• Monitor Go applications for abnormal memory usage patterns that may indicate exploitation attempts
• Implement application-level logging for math/big operations processing external input
• Use runtime memory profiling to detect sudden allocation spikes
• Review application logs for parsing errors related to rational number input

Monitoring Recommendations

• Configure alerting thresholds for memory consumption on systems running vulnerable Go applications
• Implement network intrusion detection rules to identify requests containing suspiciously large numeric strings
• Deploy application performance monitoring to track memory allocation patterns in production environments
• Establish baseline memory usage metrics for Go applications to quickly identify anomalous behavior

How to Mitigate CVE-2022-23772

Immediate Actions Required

• Upgrade Go to version 1.16.14, 1.17.7, or later immediately
• Identify all applications built with vulnerable Go versions using software composition analysis
• Implement input validation to reject numeric strings with unreasonably large exponents before parsing
• Consider rate limiting requests to services that process numeric input to reduce denial of service impact

Patch Information

The Go development team addressed this vulnerability in Go versions 1.16.14 and 1.17.7. The fix implements proper bounds checking on exponent values before memory allocation calculations occur. Organizations should upgrade to these patched versions or later releases.

Additional patch information is available through multiple vendor advisories:

• Golang Announcement
• NetApp Security Advisory ntap-20220225-0006
• Gentoo GLSA 202208-02
• Oracle Critical Patch Update July 2022

Workarounds

• Implement input validation at application boundaries to reject strings with exponents exceeding reasonable thresholds
• Use input length limits to prevent processing of extremely long numeric strings
• Deploy web application firewalls with rules to filter requests containing suspicious numeric patterns
• Isolate vulnerable applications in containers with strict memory limits to contain potential impact

# Example: Set memory limits for Go applications using cgroups
# Create a cgroup with memory limit
sudo cgcreate -g memory:/go_app_limit
sudo cgset -r memory.limit_in_bytes=2G go_app_limit

# Run Go application within memory-limited cgroup
sudo cgexec -g memory:go_app_limit ./your_go_application