When it comes to managing complex enterprise networks, Brocade Fabric OS (FOS) is well-known in the data center space. But even powerful, trusted platforms can contain critical vulnerabilities. This post breaks down CVE-2022-33185 — an exploit that lets local attackers execute arbitrary code with root privileges on vulnerable Brocade Fabric OS versions. We’ll review what the bug is, how attackers can abuse unsafe string functions, and—even if you aren’t planning to exploit it—how you can better understand real-world buffer overflow flaws.

What is CVE-2022-33185?

CVE-2022-33185 is a stack-based buffer overflow bug affecting Brocade Fabric OS versions prior to v9..1e and v9.1.. Certain device management commands use insecure C standard library functions (like strcpy, sprintf, or similar) on user inputs. An authenticated attacker with access to the local CLI can send specially-crafted arguments to those commands. These arguments can overrun the buffer, corrupt the stack, and ultimately grant control of program execution—allowing attackers to run arbitrary system code as root.

Severity: High  
Attack Vector: Local, but only requires regular shell access (not root)  
Risk: Full privilege escalation (root access), device takeover

How Does the Vulnerability Work?

The root issue comes down to unsafe string handling functions that don’t check the length of user input. Here’s the common pattern in C:

void handle_command(char *user_input) {
    char buffer[128];
    // UNSAFE: strcpy does not check length
    strcpy(buffer, user_input); 
    // ...do something with buffer
}

If an attacker supplies more than 128 characters, strcpy will write past the end of buffer, overwriting adjacent stack variables—even the return pointer. By carefully crafting this overrun data, an attacker can hijack execution flow.

In Brocade Fabric OS, some CLI commands parsed user-provided strings in exactly this way. The bug is only accessible after authentication, but any local user account suffices. Root is not required to exploit.

Attacker logs in to FOS CLI — They need any shell-eligible local account.

2. Identify vulnerable command — This may require reverse-engineering firmware or monitoring the device during input validation.
3. Pass overlong input — For instance, instead of entering mytestvalue, an attacker enters 300+ characters of attack payload.
4. Buffer overflow triggers — The unsafe function overwrites the return address or other stack control data.

Malicious code runs as root — The attacker’s payload executes with full privileges.

6. Attacker takes control — Now they can do anything on the device: manipulate fabrics, exfiltrate configs, plant persistent backdoors, you name it.

Example: Simulated Vulnerability Proof of Concept

While we can’t provide business-critical code from Brocade’s actual FOS, you can simulate similar bugs in a C environment. Here’s an educational (and dangerous) snippet highlighting the bug:

#include <stdio.h>
#include <string.h>

void vulnerable_fn(char *input) {
    char buffer[128];
    strcpy(buffer, input); // No bounds check!
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <input>\n", argv[]);
        return 1;
    }
    vulnerable_fn(argv[1]);
    printf("Command processed.\n");
    return ;
}

Danger: Never use such code in production. It’s just to illustrate the logic.

How it could be attacked

- Run: ./vulnprog $(python3 -c 'print("A"*200)')
- If compiled without stack protections, this would segfault or potentially allow injected shellcode to execute.

Real-World Exploit Example (Demo Steps)

Suppose one of the Brocade FOS CLI commands was called sethostname. If this command passes user input to an unsafe handler, the attacker could:

sethostname AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA...(repeat >128 times)...AAAAAAAAAAA

*Result:* The device crashes or, with a crafted payload, jumps to injected code.

They

- Patched affected commands to use safer functions like strncpy, snprintf, or safer string parsing logic.

Hardened stack protections.

Vendors’ advisory and fix:  
- Broadcom Security Bulletin BST000629963
- NIST NVD entry for CVE-2022-33185

More Reading and Exploit Resources

- Original Broadcom Advisory
- MITRE NVD CVE-2022-33185
- Common Buffer Overflow Examples in C

Summary

CVE-2022-33185 lets an attacker escalate to root on Brocade Fabric OS by exploiting basic C string handling errors—proving once again that classic buffer overflows remain a major risk, even on high-end enterprise hardware. Whether you run Brocade gear or not, make sure you understand these timeless flaws, patch promptly, and only grant shell access to trusted staff.

Timeline

Published on: 10/25/2022 21:15:00 UTC
Last modified on: 02/28/2023 18:01:00 UTC