CVE-2013-5745 in vino
Summary
by MITRE
The vino_server_client_data_pending function in vino-server.c in GNOME Vino 2.26.1, 2.32.1, 3.7.3, and earlier, and 3.8 when encryption is disabled, does not properly clear client data when an error causes the connection to close during authentication, which allows remote attackers to cause a denial of service (infinite loop, CPU and disk consumption) via multiple crafted requests during authentication.
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Analysis
by VulDB Data Team • 11/28/2024
The vulnerability identified as CVE-2013-5745 resides within the GNOME Vino remote desktop sharing server implementation, specifically in the vino_server_client_data_pending function located in vino-server.c. This flaw affects multiple versions of the Vino server including 2.26.1, 2.32.1, 3.7.3, and earlier releases, as well as version 3.8 when encryption is disabled. The vulnerability represents a critical security issue that stems from improper memory management during the authentication process, creating a scenario where client data remains improperly initialized or uncleared when connections are terminated due to authentication errors.
The technical implementation flaw occurs when an error condition arises during the authentication phase of the remote desktop connection process. When encryption is disabled in GNOME Vino, the server fails to properly clear or reset client data structures when authentication fails or when connections are abruptly closed. This improper handling creates a state where the server continues to process or reference stale data, leading to a condition that can result in an infinite loop. The flaw is particularly dangerous because it allows remote attackers to exploit this behavior through carefully crafted multiple requests during the authentication phase, causing the server to consume excessive CPU resources and potentially fill up disk space with repeated processing of malformed requests.
The operational impact of this vulnerability manifests as a denial of service condition that can severely degrade system performance or completely render the Vino server unavailable. The infinite loop behavior consumes significant CPU cycles continuously processing the malformed requests, while the improper data handling can lead to disk space exhaustion as the server attempts to process and store corrupted or incomplete connection data. This type of resource exhaustion attack can affect not only the remote desktop service but potentially impact the entire system performance, making it particularly dangerous in environments where Vino serves as a critical remote access tool. The vulnerability is classified under CWE-457 as "Use of Uninitialized Variable" and can be mapped to ATT&CK technique T1499.004 for "Resource Hijacking" as it consumes system resources to deny service to legitimate users.
The attack vector requires a remote attacker to send multiple crafted requests during the authentication phase while the server is in a vulnerable state, particularly when encryption is disabled. This makes the vulnerability more exploitable in environments where security best practices have not been implemented, such as disabling encryption for convenience. The lack of proper input validation and error handling in the authentication flow creates a persistent state where the server cannot properly recover from authentication failures, leading to the resource consumption patterns that characterize this denial of service vulnerability. Organizations using GNOME Vino in production environments should consider immediate mitigation through disabling the server or implementing encryption requirements, as the vulnerability exists in multiple versions and affects the core authentication mechanism of the remote desktop service.