CVE-2020-27819 : Exploit Details and Defense Strategies

An issue was discovered in libxls before and including 1.6.1 when reading Microsoft Excel files. A NULL pointer dereference vulnerability exists when parsing XLS cells in libxls/xls2csv.c:199. It could allow a remote attacker to cause a denial of service via crafted XLS file.

Understanding CVE-2020-27819

This CVE involves a vulnerability in libxls that could be exploited by a remote attacker to trigger a denial of service attack.

What is CVE-2020-27819?

The CVE-2020-27819 vulnerability is a NULL pointer dereference issue in libxls before version 1.6.2, specifically in the parsing of XLS cells, which could be abused by an attacker to disrupt services by using a maliciously crafted XLS file.

The Impact of CVE-2020-27819

The impact of this vulnerability is the potential for a remote attacker to exploit the NULL pointer dereference flaw to cause a denial of service on systems running the affected versions of libxls.

Technical Details of CVE-2020-27819

This section provides more technical insights into the vulnerability.

Vulnerability Description

The vulnerability exists in libxls before and including version 1.6.1, specifically in the parsing of XLS cells in libxls/xls2csv.c:199, leading to a NULL pointer dereference.

Affected Systems and Versions

Product: libxls
Vendor: Not applicable
Versions affected: libxls before 1.6.2

Exploitation Mechanism

The vulnerability can be exploited by a remote attacker through a crafted XLS file, triggering the NULL pointer dereference and causing a denial of service.

Mitigation and Prevention

Protecting systems from CVE-2020-27819 requires immediate actions and long-term security practices.

Immediate Steps to Take

Update libxls to version 1.6.2 or later to mitigate the vulnerability.
Be cautious when handling XLS files from untrusted sources.

Long-Term Security Practices

Regularly update software and libraries to patch known vulnerabilities.
Implement network security measures to detect and block malicious activities.

Patching and Updates

Ensure timely patching of libxls to the latest version to address the NULL pointer dereference vulnerability and enhance system security.