High Severity Flaws Patched in FreeXL Library

An update released last week for the FreeXL library patches a couple of high severity remote code execution vulnerabilities discovered by Marcin Noga, a Polish researcher working for Cisco Talos.

FreeXL is an open source C-based library that allows users to extract data from Microsoft Excel (.xls) spreadsheets. A FreeXL package is available for several Linux distributions.

Noga noticed that the read_biff_next_record and read_legacy_biff functions in FreeXL, which are related to the Binary Interchange File Format (BIFF), are affected by heap-based buffer overflow vulnerabilities. An attacker can exploit the flaws by getting the targeted user to open a specially crafted Excel file via an application that uses the FreeXL library.

“An attacker who sends a malicious XLS file, can use this to overwrite large parts of memory to crash the application or to execute arbitrary code by overwriting critical control flow structures,” Cisco said in a blog post.

The flaws, tracked as CVE-2017-2923 and CVE-2017-2924, have been assigned a CVSS score of 8.8, which puts them in the high severity category. Cisco Talos has published technical advisories for both security holes.

The vulnerabilities were patched by FreeXL developers on September 7 with the release of version 1.0.4.

“Developers, system packagers and maintainers are warmly invited to quickly upgrade to FreeXL-1.0.4,” said FreeXL maintainer and developer Alessandro Furieri.

FreeXL vulnerabilities are uncommon, but not unheard of. Back in March 2015, a researcher discovered several flaws that could have been exploited for arbitrary code execution or denial-of-service (DoS) attacks by getting the targeted user to open a specially crafted file.

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Eduard Kovacs is an international correspondent for SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.

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