CVE-2015-2785 in Byzanz
Summary
by MITRE
The GIF encoder in Byzanz allows remote attackers to cause a denial of service (out-of-bounds heap write and crash) or possibly execute arbitrary code via a crafted Byzanz debug data recording (ByzanzRecording file) to the byzanz-playback command.
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Analysis
by VulDB Data Team • 04/15/2018
The vulnerability identified as CVE-2015-2785 resides within the GIF encoder component of the Byzanz screen recording tool, a utility commonly used for creating animated GIFs from screen captures. This flaw manifests as a critical security issue that can be exploited remotely by attackers who craft malicious Byzanz debug data recording files. The vulnerability specifically affects the byzanz-playback command which processes these debug recording files, creating a potential attack surface that could be leveraged for serious system compromise. The flaw represents a significant concern for users who might encounter untrusted Byzanz recording files, particularly in environments where automated processing or sharing of screen recordings occurs.
The technical nature of this vulnerability involves an out-of-bounds heap write condition that occurs during the processing of specially crafted Byzanz debug data files. When the byzanz-playback command attempts to decode and render these malicious files, the GIF encoder fails to properly validate input data boundaries, leading to memory corruption. This heap buffer overflow condition can result in unpredictable program behavior, including application crashes and potential system instability. The vulnerability's severity is amplified by the fact that it can potentially allow for arbitrary code execution, making it particularly dangerous for attackers who wish to gain unauthorized access to affected systems. The flaw stems from inadequate input validation mechanisms within the GIF encoding logic, where the system does not properly sanitize or bounds-check the data structures used during the decoding process.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it creates opportunities for remote code execution that could be leveraged by threat actors to compromise entire systems. Organizations using Byzanz for screen recording and sharing activities face significant risk when processing untrusted files, particularly in collaborative environments or when receiving external screen captures. The vulnerability affects systems where Byzanz is installed and where users might encounter maliciously crafted Byzanz debug recording files, potentially through email attachments, file sharing platforms, or automated processing systems. Security teams must consider the broader implications of this flaw when assessing their attack surface, as it could be exploited in supply chain attacks or social engineering campaigns targeting users who regularly interact with screen recording tools.
Mitigation strategies for CVE-2015-2785 should focus on immediate patching of affected systems, as the vulnerability has been addressed through software updates that include proper input validation and bounds checking mechanisms. Organizations should implement strict file validation procedures for any Byzanz recording files that are processed automatically or received from untrusted sources. Network segmentation and access controls can help limit the potential impact of exploitation attempts, while security monitoring should be enhanced to detect unusual file processing activities that might indicate exploitation attempts. The vulnerability aligns with CWE-121, heap-based buffer overflow, and could be mapped to ATT&CK techniques involving execution through malicious file processing or privilege escalation. Regular security assessments and vulnerability scanning should include checks for outdated Byzanz installations, while user education regarding the risks of processing untrusted screen recording files remains crucial for comprehensive defense. System administrators should also consider implementing sandboxing or containerization approaches for processing potentially malicious files to contain any potential exploitation attempts.