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The vulnerability resides in the partition firmware component of IBM PowerVM Hypervisor, specifically within the iSCSI SAN network boot implementation. Affected firmware versions include FW1120.00, FW1110.00 through FW1110.30, FW1060.00 through FW1060.80, and FW950.00 through FW950.H2. The core issue is an out‑of‑bounds read (CWE‑125) triggered when the partition firmware processes certain network packets during the iSCSI boot phase. An unauthenticated attacker with layer‑2 adjacency (same network segment) can exploit this flaw without any prior credentials or user interaction. The attack vector is adjacent network (AV:A), with low attack complexity (AC:L), and requires no privileges (PR:N) or user involvement (UI:N). The scope is unchanged (S:U), and the impact is strictly on availability (A:H) with no effect on confidentiality or integrity. During the iSCSI SAN boot, the partition firmware sends and receives iSCSI PDUs over TCP to discover targets, login, and read the boot image. By injecting a specially crafted iSCSI PDU or a malformed network packet that the firmware parses, the attacker can cause the firmware’s parsing routine to read beyond the allocated buffer. This out‑of‑bounds read leads to a firmware crash or an infinite hang, preventing the partition from completing its boot sequence. The crash occurs early in the boot process, meaning the affected partition never reaches the operating system loader. Importantly, other partitions running on the same physical managed system remain unaffected because the vulnerability is isolated to the partition’s own firmware instance. The managed system’s hypervisor and hardware management console continue to operate normally. Only partitions that are actively attempting an iSCSI SAN network boot are susceptible; partitions that boot from local disk, SAN fibre channel, or other methods are not exposed. The vulnerability does not allow arbitrary code execution or data exfiltration; it is a pure denial‑of‑service condition. An attacker can repeatedly send malicious packets to keep the target partition from ever booting, effectively rendering it unusable until the boot source is changed or the firmware is updated. The CVSS 3.1 base score is 6.5 (Medium) due to the availability impact and adjacent attack vector. IBM has acknowledged the issue and released security bulletins recommending firmware upgrades. The flaw affects a wide range of Power Systems, including S922, S924, E950, E980, and many other models listed in the CPE configurations. Given the nature of iSCSI boot in enterprise environments, this vulnerability poses a significant operational risk for data centers relying on network‑based boot for IBM Power servers.
DailyCVE Form:
Platform: IBM PowerVM Hypervisor
Version: FW1120.00, FW1110.00-30, FW1060.00-80, FW950.00-H2
Vulnerability: Out-of-bounds Read
Severity: Medium (CVSS 6.5)
date: 2023-09-19
Prediction: 2023-10-31
What Undercode Say:
Check current firmware version on PowerVM
lsfw -p
Scan local network for iSCSI booting partitions (discovery)
nmap -p 3260 –script=iscsi-info 192.168.1.0/24
Monitor iSCSI boot traffic for anomaly detection
tcpdump -i eth0 -nn port 3260 -vv
Simulate malformed iSCSI PDU using Scapy (proof of concept)
from scapy.all import
p = IP(dst=”192.168.1.100″)/TCP(dport=3260)/Raw(load=”\x00″1024 + “\x41″4096)
send(p, loop=1, inter=0.1)
Check system logs for partition boot failures
errpt -a | grep -i iscsi
Exploit: (Educational Purposes!)
An attacker on the same broadcast domain crafts a series of iSCSI login or data‑in PDUs with oversized or malformed header fields. By sending these packets to the target partition’s iSCSI listening port (3260) during the boot window, the firmware’s parsing loop reads beyond the intended buffer due to a missing boundary check. This causes a memory access violation that halts the boot process. For example, a PDU with a reported data segment length larger than the actual payload forces the parser to read past the heap allocation, leading to a hard lock. The attack requires timing to coincide with the boot sequence, but repeated bursts ensure disruption. No authentication is required, and the attacker does not need to spoof IP addresses—raw Ethernet frames suffice. This is a resource exhaustion‑style DoS, but the root cause is a software bug in the firmware’s iSCSI stack.
Protection: from this CVE
Upgrade the partition firmware to versions FW1120.10 (or later), FW1110.40, FW1060.90, or FW950.H3 as per IBM advisory. If immediate patching is not possible, restrict network access to the iSCSI boot VLAN using private VLANs or 802.1X port security. Disable iSCSI SAN boot on partitions that do not require it and use alternative boot methods (e.g., local disk, FC SAN). Deploy network intrusion detection rules to alert on anomalous iSCSI traffic patterns. Enable firmware integrity verification and use secure boot configurations where available. Isolate management and boot networks from general‑purpose user networks to limit the attack surface. Regularly monitor boot logs for unexpected failures that may indicate attempted exploitation.
Impact:
Successful exploitation prevents the targeted logical partition (LPAR) from completing its boot sequence, causing a denial of service. The partition remains in a stalled or crashed state until manually reset or its boot source is changed. The managed system and all other partitions continue to operate without interruption. There is no data breach, privilege escalation, or hypervisor compromise. Operational impact is limited to the availability of the specific LPAR, which can be critical for workloads with high‑availability requirements. Recovery requires administrator intervention to stop the boot loop and either apply the firmware fix or switch to a non‑iSCSI boot device. In a worst‑case scenario, repeated attacks can indefinitely block production workloads, leading to extended downtime and potential service‑level agreement violations.
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Sources:
Reported By: nvd.nist.gov
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