CVE-2024-33599: GNU Glibc Buffer Overflow Vulnerability

CVE-2024-33599 Overview

CVE-2024-33599 is a stack-based buffer overflow vulnerability in the Name Service Cache Daemon (nscd) component of GNU C Library (glibc). When nscd's fixed-size cache becomes exhausted by client requests, a subsequent client request for netgroup data can trigger a stack-based buffer overflow condition. This flaw was introduced in glibc 2.15 when the netgroup cache functionality was added to nscd.

The vulnerability exists exclusively within the nscd binary, which is commonly deployed on Linux systems to provide caching for name service lookups such as passwd, group, hosts, and netgroup information.

Critical Impact

A network-accessible stack-based buffer overflow in nscd could allow remote attackers to crash the daemon or potentially execute arbitrary code on vulnerable systems running glibc 2.15 and later versions.

Affected Products

• GNU glibc (versions 2.15 and later)
• Debian Linux 10.0
• NetApp H300s, H500s, H700s, H410s, H410c (firmware)
• NetApp HCI Bootstrap OS

Discovery Timeline

• 2024-05-06 - CVE-2024-33599 published to NVD
• 2025-06-18 - Last updated in NVD database

Technical Details for CVE-2024-33599

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), a memory corruption flaw that occurs when the nscd netgroup cache reaches its capacity limit. The stack-based nature of this overflow makes it particularly dangerous, as stack memory contains critical program control data including return addresses and saved frame pointers.

The attack requires network access and involves high complexity, as the attacker must first exhaust nscd's fixed-size cache through legitimate or malicious client requests before triggering the overflow condition with a crafted netgroup data request. This two-stage exploitation requirement introduces timing and race condition challenges for successful exploitation.

The vulnerability affects the confidentiality, integrity, and availability of the target system. Successful exploitation could lead to denial of service through daemon crashes, information disclosure from memory corruption, or potentially arbitrary code execution if an attacker can precisely control the overflow data.

Root Cause

The root cause stems from improper bounds checking in nscd's netgroup cache handling code. When the cache is exhausted and a new netgroup request arrives, the code fails to properly validate buffer boundaries before writing data to stack-allocated memory. This condition was introduced in glibc 2.15 when the netgroup caching functionality was implemented.

The fixed-size cache design creates a predictable state where the vulnerability can be triggered, as attackers can intentionally fill the cache to set up the overflow condition.

Attack Vector

The attack vector is network-based, targeting systems running nscd with netgroup caching enabled. An attacker can remotely interact with nscd through standard NSS (Name Service Switch) client requests.

The exploitation flow involves:

1. The attacker sends numerous requests to exhaust nscd's fixed-size cache
2. Once the cache reaches capacity, a specially crafted netgroup data request is sent
3. The cache exhaustion condition combined with the netgroup request triggers the stack-based buffer overflow
4. Depending on the overflow payload, this can result in daemon crash, memory corruption, or potential code execution

The vulnerability mechanism involves improper memory management when the netgroup cache is full. Technical details regarding the specific overflow condition can be found in the glibc Advisory Document and the Openwall Security Discussion.

Detection Methods for CVE-2024-33599

Indicators of Compromise

• Unexpected nscd daemon crashes or restarts
• Abnormally high volume of netgroup lookup requests in system logs
• Memory access violations or segmentation faults in nscd process
• Unusual cache fill patterns indicating deliberate cache exhaustion attempts

Detection Strategies

• Monitor nscd process for abnormal termination signals (SIGSEGV, SIGABRT)
• Implement network traffic analysis to detect high-frequency netgroup requests from single sources
• Deploy memory protection mechanisms such as ASLR and stack canaries to increase exploitation difficulty
• Use process monitoring tools to track nscd memory usage and cache statistics

Monitoring Recommendations

• Enable detailed logging for nscd operations including cache hit/miss ratios
• Configure alerting for nscd service restarts or unexpected terminations
• Implement rate limiting on NSS client requests where operationally feasible
• Monitor for exploit activity using endpoint detection solutions like SentinelOne Singularity

How to Mitigate CVE-2024-33599

Immediate Actions Required

• Update glibc to a patched version that addresses CVE-2024-33599
• Disable nscd netgroup caching if not required for operations
• Restrict network access to nscd through firewall rules where possible
• Review and apply vendor-specific patches for affected NetApp and Debian systems

Patch Information

GNU glibc maintainers have released patches addressing this vulnerability. Affected organizations should consult the glibc Advisory Document for official patch details.

Debian users should refer to the Debian LTS Announcement for distribution-specific updates.

NetApp customers should review the NetApp Security Advisory for firmware update information.

Workarounds

• Disable the nscd service entirely if name service caching is not operationally required
• Disable netgroup caching specifically by setting enable-cache netgroup no in /etc/nscd.conf
• Implement network segmentation to limit exposure of systems running nscd
• Deploy endpoint protection to detect and block exploitation attempts

# Disable netgroup caching in nscd configuration
echo "enable-cache netgroup no" >> /etc/nscd.conf
systemctl restart nscd

# Alternatively, disable nscd entirely if not required
systemctl stop nscd
systemctl disable nscd