CVE-2015-7698 in icewind1991 SMB
Summary
by MITRE
icewind1991 SMB before 1.0.3 allows remote authenticated users to execute arbitrary SMB commands via shell metacharacters in the user argument in the (1) listShares function in Server.php or the (2) connect or (3) read function in Share.php.
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Analysis
by VulDB Data Team • 11/17/2024
The vulnerability identified as CVE-2015-7698 affects the icewind1991 SMB library version 1.0.2 and earlier, representing a critical command injection flaw that enables authenticated remote attackers to execute arbitrary SMB commands through improper input validation. This vulnerability resides within the server-side SMB implementation and specifically targets three distinct functions across different PHP files within the library structure. The flaw manifests when user-supplied arguments containing shell metacharacters are processed without adequate sanitization or escaping mechanisms, creating a direct pathway for command injection attacks.
The technical implementation of this vulnerability stems from the lack of proper input validation and sanitization within the SMB library's core functions. When the listShares function in Server.php processes user arguments, or when the connect and read functions in Share.php handle user input, the library fails to properly escape or filter shell metacharacters that may be present in the user argument. This creates a classic command injection vulnerability where malicious input can be interpreted by the underlying shell as executable commands rather than simple data. The vulnerability is particularly concerning because it requires only authenticated access, meaning that any user with valid SMB credentials can exploit this flaw to execute arbitrary commands on the target system.
The operational impact of this vulnerability extends beyond simple command execution, as it provides attackers with significant control over the affected system. Successful exploitation allows adversaries to execute arbitrary code with the privileges of the SMB service account, potentially leading to complete system compromise. This vulnerability aligns with CWE-77 and CWE-78 categories, which specifically address command injection flaws where untrusted data is incorporated into system commands without proper sanitization. The attack vector is particularly dangerous in enterprise environments where SMB services are commonly used for file sharing and network communication, as it can enable lateral movement and privilege escalation attacks.
From an ATT&CK framework perspective, this vulnerability maps to multiple techniques including T1059.001 for command and script injection, T1068 for exploit for privilege escalation, and T1021.002 for SMB/Windows Admin Shares. The vulnerability's exploitation requires authentication, which aligns with T1078 for valid accounts and T1566 for phishing with a credential. Organizations with SMB services running the vulnerable icewind1991 library are at significant risk, as this vulnerability can be exploited by attackers who have obtained legitimate SMB credentials through various means including credential theft, social engineering, or brute force attacks. The impact is particularly severe in environments where SMB is used for critical file sharing operations, as attackers could potentially access sensitive data, modify files, or establish persistent access through the executed commands.
Mitigation strategies for this vulnerability should include immediate patching of the icewind1991 SMB library to version 1.0.3 or later, which contains the necessary input sanitization fixes. Organizations should also implement network segmentation to limit SMB access to necessary systems only, enforce strong authentication mechanisms including multi-factor authentication, and monitor SMB traffic for suspicious command execution patterns. Additionally, network-based intrusion detection systems should be configured to detect potential exploitation attempts through monitoring of SMB protocol anomalies. Regular security assessments and vulnerability scanning should be conducted to identify other potentially vulnerable components within the SMB ecosystem, and access controls should be reviewed to ensure least privilege principles are enforced. The remediation process should also include reviewing and implementing proper input validation and output encoding practices throughout the application codebase to prevent similar vulnerabilities from emerging in other components.