Earlier this year, a serious vulnerability—CVE-2024-47115—was published, targeting enterprise environments running IBM’s AIX and VIOS systems. This flaw allows any local user, even those with limited privileges, to execute arbitrary commands on the affected system. The crux of the issue? Improper neutralization of input data, otherwise known as command injection.
In this post, we’ll break down what’s going on, how an attacker can exploit it, and offer some actionable advice.
What Is CVE-2024-47115?
On May 31st, 2024, IBM announced (see security advisory), that specific versions of AIX and VIOS are vulnerable to a command injection risk. The vulnerable software includes:
IBM AIX: Versions 7.2 and 7.3
- IBM VIOS (Virtual I/O Server): Versions 3.1 and 4.1
A local attacker, using carefully crafted input, can trick the system into running arbitrary shell commands—potentially leading to privilege escalation, data theft, or system compromise.
Where’s the Problem?
The vulnerability is caused by a system utility script or program failing to properly “sanitize” user input. Instead of treating everything as harmless text, it trusts input that may contain dangerous shell characters (like ;, &&, or |). If that input is passed to the shell without cleaning, the attacker injects and runs commands.
Let’s look at a simplified example
// Hypothetical vulnerable C function
void run_backup(char *filename) {
char cmd[512];
snprintf(cmd, sizeof(cmd), "/usr/bin/backup -f %s", filename);
system(cmd); // BAD: direct use of unsanitized input
}
If the attacker sets filename like
"backup.tar; rm -rf /important/data;"
The command would execute
/usr/bin/backup -f backup.tar; rm -rf /important/data;
This not only backs up data, but also deletes a critical directory. This is the essence of a command injection bug.
### Realistic VIOS/AIX Example
In reality, system utilities on AIX/VIOS, such as user management scripts or backup tools, sometimes get input from local users or scripts. If this input isn’t sanitized, a determined attacker can break out of the expected behavior.
How Can Attackers Exploit This?
Scenario:
A user with shell access (even nobody) finds a SUID-root script or system tool using unsafe input.
Locate vulnerable utility
Find a script or tool vulnerable to command injection. Sometimes, automated scans or simple source code review can spot these.
Craft malicious input
Choose an input field (filename, device name, username, etc.) and inject shell metacharacters (;, |, or &&) along with malicious commands.
Run the command
Invoke the utility with your crafted input. If it isn’t sanitized, your injected commands run as the privileged user.
Suppose there’s a maintenance script owned by root executable by local users
$ /usr/bin/myscript.sh "myfile; id"
If the script simply does
backup_file=$1
tar cf /backup/$backup_file
This command would actually execute tar cf /backup/myfile AND also execute id, showing the current user.
Proof of Concept (POC) – Demonstration
Let’s simulate how an attacker might abuse this flaw.
# Assume 'vulnbak' is a setuid-root backup utility that takes a filename:
$ vulnbak "safe.tar; touch /tmp/root_was_here"
# After running, check if the file was created:
$ ls -l /tmp/root_was_here
-rw-r--r-- 1 root system Jun 3 14:23 /tmp/root_was_here
If the file /tmp/root_was_here exists and is owned by root, the system is vulnerable.
To escalate, attackers might use
vulnbak "file.tar; cp /bin/sh /tmp/rootsh; chmod +s /tmp/rootsh"
# Now, /tmp/rootsh is a root shell
IBM has issued fixes. Patch immediately
- AIX 7.2 & 7.3 APARs
- VIOS 3.1 & 4.1 Fixes
Temporary mitigations
- Limit access to SUID/SGID scripts and sensitive utilities.
IBM Official Advisory:
IBM Security Bulletin: AIX/VIOS Improper Neutralization of Input
CVE-2024-47115 Record:
Command Injection basics:
Final Thoughts
Even mature, enterprise-class UNIX systems like AIX and VIOS aren’t immune to classic bugs like command injection. Make sure you patch soon, restrict unnecessary shell/script access, and regularly review your systems for unpatched SUID/SGID tools. This bug is easy to exploit—don’t leave your systems open!
If you have questions or find something interesting in your environment, join the conversation and share what you’re seeing.
*This article is exclusive, written for those looking to understand and defend against CVE-2024-47115 in simple, practical terms.*
Timeline
Published on: 12/07/2024 13:19:14 UTC