CVE-2008-0097 in SSH2 Server
Summary
by MITRE
Format string vulnerability in the log function in Georgia SoftWorks SSH2 Server (GSW_SSHD) 7.01.0003 and earlier allows remote attackers to execute arbitrary code via format string specifiers in the username field, as demonstrated by a certain LoginPassword message.
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Analysis
by VulDB Data Team • 08/02/2019
The vulnerability identified as CVE-2008-0097 represents a critical format string flaw within the Georgia SoftWorks SSH2 Server version 7.01.0003 and earlier releases. This type of vulnerability falls under the Common Weakness Enumeration category CWE-134 which specifically addresses the use of format strings with user-supplied data without proper validation or sanitization. The vulnerability manifests in the server's logging function where the username field is processed without adequate input validation, creating a pathway for malicious exploitation.
The technical implementation of this vulnerability occurs when the SSH server processes login attempts and logs the username information. Attackers can manipulate the username field to include format string specifiers such as %s, %x, or %n which are typically used to control output formatting in C language functions like printf. When these malicious specifiers are passed through the vulnerable logging function, they can trigger unintended behavior in the server's memory management. The attacker can leverage this to read arbitrary memory locations, overwrite critical memory areas, or even execute arbitrary code within the context of the SSH server process.
The operational impact of this vulnerability is severe and multifaceted. Remote attackers can exploit this flaw to gain unauthorized access to the affected server, potentially leading to complete system compromise. The vulnerability allows for privilege escalation and persistent access, making it particularly dangerous in environments where SSH servers are used for administrative access. The attack vector is straightforward as it requires only a standard SSH client to connect to the vulnerable server and provide a specially crafted username during authentication. This vulnerability directly aligns with MITRE ATT&CK technique T1078 which covers valid accounts and T1046 which covers network service scanning, as attackers can identify and exploit this vulnerability without requiring elevated privileges initially.
Mitigation strategies for this vulnerability must be comprehensive and immediate. The primary recommendation involves upgrading to a patched version of the Georgia SoftWorks SSH2 Server, as the vendor has released updates addressing this specific format string vulnerability. Organizations should also implement network segmentation and access controls to limit exposure of vulnerable SSH servers to untrusted networks. Additional defensive measures include monitoring login attempts for suspicious username patterns that might indicate exploitation attempts, implementing intrusion detection systems that can identify format string attack patterns, and conducting regular vulnerability assessments to identify other potential instances of similar flaws in the system infrastructure. The vulnerability demonstrates the critical importance of input validation and proper string handling in security-sensitive applications, particularly those handling authentication and logging functions.