CVE-2017-17840 in open-iscsi
Summary
by MITRE
An issue was discovered in Open-iSCSI through 2.0.875. A local attacker can cause the iscsiuio server to abort or potentially execute code by sending messages with incorrect lengths, which (due to lack of checking) can lead to buffer overflows, and result in aborts (with overflow checking enabled) or code execution. The process_iscsid_broadcast function in iscsiuio/src/unix/iscsid_ipc.c does not validate the payload length before a write operation.
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Analysis
by VulDB Data Team • 12/18/2019
The vulnerability identified as CVE-2017-17840 represents a critical buffer overflow flaw within the Open-iSCSI software suite, specifically affecting versions through 2.0.875. This issue resides in the iscsiuio server component which serves as a user-space interface for iSCSI operations. The vulnerability stems from inadequate input validation mechanisms within the process_iscsid_broadcast function located in the iscsiuio/src/unix/iscsid_ipc.c source file, creating a pathway for malicious exploitation through crafted message manipulation.
The technical flaw manifests when the iscsiuio server receives messages containing incorrect payload lengths without proper validation checks. This lack of payload length verification creates a condition where buffer overflow conditions can be triggered during write operations. When overflow checking is enabled, the vulnerability results in process aborts, but with overflow checking disabled, the flaw can potentially enable arbitrary code execution. The vulnerability operates at the kernel-user space boundary where iSCSI communication occurs, making it particularly dangerous as it can be exploited by local attackers who have access to the system.
The operational impact of this vulnerability extends beyond simple denial of service scenarios. A local attacker with sufficient privileges can leverage this flaw to execute arbitrary code with the privileges of the iscsiuio server process, potentially leading to complete system compromise. The vulnerability affects systems running Open-iSCSI implementations that utilize the iscsiuio server component, which is commonly deployed in enterprise storage environments where iSCSI connectivity is utilized for block-level storage access. The nature of this vulnerability means that any system where the iscsiuio server is actively running and processing iSCSI messages presents a potential attack surface for exploitation.
This vulnerability aligns with CWE-121, which describes "Stack-based Buffer Overflow" conditions, and represents a classic example of improper input validation leading to memory corruption. From an ATT&CK perspective, this vulnerability maps to T1059.007 for Command and Scripting Interpreter: PowerShell and T1068 for Exploitation for Privilege Escalation, as local attackers can exploit the buffer overflow to execute code. The vulnerability also corresponds to T1547.001 for Registry Run Keys / Startup Folder, as exploitation could lead to persistence mechanisms being established. Organizations should prioritize patching this vulnerability, as it represents a significant risk to storage infrastructure security where Open-iSCSI is deployed. The recommended mitigation strategy involves upgrading to a patched version of Open-iSCSI beyond version 2.0.875, implementing network segmentation to limit local access, and monitoring for suspicious iSCSI communication patterns that might indicate exploitation attempts.