CVE-2013-6836 in Gnumeric
Summary
by MITRE
Heap-based buffer overflow in the ms_escher_get_data function in plugins/excel/ms-escher.c in GNOME Office Gnumeric before 1.12.9 allows remote attackers to cause a denial of service (crash) via a crafted xls file with a crafted length value.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 01/18/2022
The vulnerability CVE-2013-6836 represents a critical heap-based buffer overflow flaw discovered in the GNOME Office Gnumeric spreadsheet application. This vulnerability specifically affects the ms_escher_get_data function located within the plugins/excel/ms-escher.c file, which is responsible for processing Microsoft Excel file formats. The flaw manifests when Gnumeric processes crafted xls files containing manipulated length values that exceed the allocated buffer boundaries. This issue falls under the CWE-121 heap-based buffer overflow category, which is classified as a serious memory corruption vulnerability that can lead to arbitrary code execution or system instability.
The technical implementation of this vulnerability exploits the lack of proper input validation within the ms_escher_get_data function. When Gnumeric encounters a malformed xls file with an oversized length field, the application fails to perform adequate boundary checks before attempting to allocate memory or copy data into heap buffers. The function processes the Excel file's Escher (Extensible Storage Engine) data structure without sufficient validation of the length parameters, allowing attackers to manipulate the memory allocation process. This creates a situation where the application attempts to write more data than the allocated buffer can accommodate, resulting in memory corruption that typically manifests as application crashes or segmentation faults. The vulnerability is particularly dangerous because it operates entirely within the file parsing logic, making it accessible through standard file processing operations without requiring any special privileges or user interaction beyond opening the malicious file.
From an operational perspective, this vulnerability poses significant risks to users of GNOME Office Gnumeric, particularly in environments where automated file processing or email attachment handling occurs. The denial of service impact means that legitimate users can be disrupted through simple file-based attacks, potentially affecting productivity and system availability. Attackers could craft malicious xls files that would cause Gnumeric to crash whenever opened, creating a reliable method for disrupting normal operations. The vulnerability affects all versions of Gnumeric prior to 1.12.9, making it a persistent threat for organizations that have not updated their software. This type of vulnerability aligns with ATT&CK technique T1203, which describes the use of malicious files to cause system instability or denial of service, and demonstrates how file format parsing vulnerabilities can be exploited for operational disruption.
The mitigation strategy for CVE-2013-6836 primarily involves updating to Gnumeric version 1.12.9 or later, which contains the necessary patches to address the buffer overflow condition. Organizations should implement comprehensive software update policies to ensure all instances of Gnumeric are patched promptly, particularly in environments where users may encounter untrusted Excel files. System administrators should also consider implementing additional security controls such as file type validation, sandboxing of file processing operations, and network-based filtering of suspicious file attachments. The vulnerability highlights the importance of proper input validation and memory management practices in file processing applications, as recommended by industry standards such as the OWASP Top Ten and the CERT Secure Coding Standards. Additionally, organizations should conduct regular security assessments of their office productivity software to identify and remediate similar vulnerabilities that may exist in other applications within their computing environment.