CVE-2007-3833 in Trillian
Summary
by MITRE
The AOL Instant Messenger (AIM) protocol handler in Cerulean Studios Trillian allows remote attackers to create files with arbitrary contents via certain aim: URIs, as demonstrated by a URI that begins with the "aim: &c:\" substring and contains a full pathname in the ini field. NOTE: this can be leveraged for code execution by writing to a Startup folder.
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Analysis
by VulDB Data Team • 06/07/2025
The vulnerability described in CVE-2007-3833 represents a critical file system manipulation flaw within the AOL Instant Messenger protocol handler implementation in Cerulean Studios Trillian messaging client. This security weakness stems from insufficient input validation and sanitization of URI parameters, specifically affecting the aim: URI scheme parsing mechanism. The vulnerability is particularly concerning as it enables remote attackers to craft malicious URIs that can manipulate file creation operations on the target system. The exploit technique involves constructing a specially formatted URI beginning with "aim: &c:\" followed by a full pathname in the ini field parameter, which allows arbitrary file creation with potentially malicious content.
The technical exploitation of this vulnerability occurs through the improper handling of URI parsing within Trillian's protocol handler component. When the application processes a malicious aim: URI, it fails to properly validate or sanitize the pathname parameter contained within the ini field, leading to potential directory traversal and file creation operations. This flaw operates at the application level protocol handler, where the software incorrectly interprets user-supplied URI parameters as legitimate file system commands rather than treating them as potentially malicious input. The vulnerability demonstrates a classic case of insufficient input validation, which is categorized under CWE-20 as "Improper Input Validation" and falls within the broader category of CWE-74 as "Improper Neutralization of Special Elements in Output Used by a Downstream Component."
The operational impact of this vulnerability extends beyond simple file creation capabilities to encompass potential code execution scenarios. Attackers can leverage this flaw to write malicious files to the Windows Startup folder or other system directories, effectively enabling persistence mechanisms and automatic execution of malicious code upon system reboot. This represents a significant escalation from simple file manipulation to full system compromise, as the attacker can place executable files in locations where they will automatically execute without user interaction. The vulnerability's exploitability is enhanced by the fact that it requires no special privileges or user interaction beyond the simple act of processing a malicious URI, making it particularly dangerous in social engineering scenarios.
From a cybersecurity perspective, this vulnerability aligns with several ATT&CK framework techniques including T1059 for command and script interpreter execution and T1068 for exploit for privilege escalation. The attack chain typically begins with initial compromise through phishing or malicious website delivery of the crafted URI, followed by automatic execution of malicious payloads through the Windows startup mechanism. The vulnerability also relates to T1547 as it enables persistence through modification of startup folders, and T1083 as it allows for directory traversal and file system enumeration. Organizations should recognize this as a precursor to more sophisticated attacks, as the initial file creation can be used to establish a foothold for further exploitation and lateral movement within compromised networks.
Mitigation strategies for CVE-2007-3833 should focus on both immediate patching and operational security measures. The primary recommendation involves updating Trillian to a version that properly validates and sanitizes URI parameters before processing them as file system operations. Additionally, system administrators should implement strict URI handling policies, particularly for applications that process external protocols, and consider disabling unnecessary protocol handlers when possible. Network-level controls such as URI filtering and content inspection can provide additional protection against exploitation attempts. Organizations should also implement monitoring for unusual file creation patterns in startup folders and other system directories, as these activities may indicate successful exploitation attempts. The vulnerability highlights the importance of secure coding practices and input validation, particularly for applications that process external data sources and protocol handlers that interact directly with the file system.