CVE-2007-4310 in Solaris
Summary
by MITRE
The finger daemon (in.fingerd) in Sun Solaris 7 through 9 allows remote attackers to list all accounts that have certain nonstandard GECOS fields via a request composed of a single digit, as demonstrated by a "finger 9@host" command, a different vulnerability than CVE-2001-1503.
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Analysis
by VulDB Data Team • 08/01/2019
The finger daemon in Sun Solaris versions 7 through 9 contains a significant information disclosure vulnerability that enables remote attackers to enumerate user accounts with specific GECOS field configurations. This vulnerability operates through a carefully crafted request format where a single digit character triggers the daemon to return account information for users whose GECOS fields contain certain nonstandard values. The attack vector specifically involves executing a command such as "finger 9@host" which demonstrates the daemon's improper handling of numeric input parameters. Unlike CVE-2001-1503 which addressed different aspects of finger daemon vulnerabilities, this particular flaw represents a distinct attack surface that exploits the daemon's parsing behavior when encountering single-digit requests. The vulnerability stems from insufficient input validation and improper access control mechanisms within the finger daemon's processing logic, allowing unauthorized users to gain insights into the system's user base beyond what should be publicly accessible.
The technical implementation of this vulnerability occurs at the daemon level where the in.fingerd service fails to properly sanitize or validate the input parameters before processing them against the system's user database. When a numeric character is provided as the primary request parameter, the daemon interprets this input in a manner that causes it to traverse and return account information for users whose GECOS fields contain specific patterns or values. This behavior represents a classic example of improper input validation and inadequate privilege separation, where the daemon operates with elevated privileges to access user account information but fails to properly restrict the scope of information disclosure. The vulnerability specifically affects systems where users have configured their GECOS fields with certain nonstandard values, making the attack surface dependent on the specific configuration of user accounts within the target system. This flaw operates at the application layer and demonstrates weaknesses in the daemon's request parsing and response generation mechanisms.
The operational impact of this vulnerability extends beyond simple information gathering as it provides attackers with valuable reconnaissance data that can be used in subsequent attack phases. By enumerating accounts with specific GECOS field configurations, attackers can identify potential targets for further exploitation or social engineering campaigns. The vulnerability allows for systematic account discovery without requiring authentication, making it particularly dangerous in environments where the finger service remains enabled. This information disclosure can facilitate password spraying attacks, targeted phishing campaigns, or other social engineering initiatives that rely on knowledge of valid user accounts. The vulnerability also represents a violation of the principle of least privilege since the daemon should only provide information that is explicitly intended to be public, but instead reveals detailed account information based on specific field configurations. From a compliance perspective, this vulnerability could lead to violations of security standards such as those outlined in the NIST Cybersecurity Framework and ISO 27001 requirements for information access control.
Mitigation strategies for this vulnerability should focus on disabling the finger service entirely if it is not required for business operations, as this represents the most effective solution. System administrators should ensure that the in.fingerd daemon is either disabled or properly configured with restricted access controls to prevent unauthorized enumeration. The recommended approach involves implementing proper network segmentation to restrict access to the finger service to trusted networks only, or completely removing the service from production environments where it is not essential. Additionally, security configurations should enforce strict input validation on all daemon services to prevent similar vulnerabilities from manifesting in other components. Organizations should also conduct regular vulnerability assessments to identify and remediate similar issues in other system services, particularly those that handle user account information or system enumeration requests. This vulnerability aligns with CWE-20, which describes improper input validation, and represents a specific instance of how insufficient validation can lead to information disclosure. The ATT&CK framework categorizes this as a reconnaissance technique under the T1087 enumeration category, where adversaries gather information about the target environment through automated tools and service enumeration. Proper patch management and service hardening practices should be implemented to prevent exploitation of this and similar vulnerabilities in the broader attack surface.