Sign up for free and start receiving your daily dose of cybersecurity news, insights. LibreOffice and OpenOffice have released fixes to tackle an issue that allows hackers to make documents look as if they were signed by a trustworthy source.Įven though the vulnerability is not placed in the ‘High’ severity category being rated as moderate, the consequences could be disastrous. Severe RCE Flaw Disclosed in Popular LibreOffice and OpenOffice Software. The digital signatures used in document macros are intended to assist the user in determining whether or not a document has been modified and can be trustworthy.Īllowing anyone to sign macro-ridden documents themselves, and make them appear as trustworthy, is an excellent way to trick users into running malicious code. Ruhr University Bochum’s cybersecurity researchers were the first to notice this vulnerability in OpenOffice, which has been tracked as CVE-2021-41832. The same issue affects LibreOffice, a project fork of OpenOffice that originated from the main project over ten years ago and is recorded as CVE-2021-25635 for their project. For LibreOffice – 7.0.5 or 7.1.1 and later.Those using at least one of the open-source office suites are recommended to update to the most recent version as quickly as possible. Users will have to do the updates manually by downloading the newest version from the LibreOffice, OpenOffice download centers, as neither LibreOffice nor OpenOffice apps provide auto-updating. They can be recommended if you want an open-source office suite with a word processor, spreadsheet, presentation, and a few other programs. Those using Linux who don’t have the versions mentioned above available on their distribution’s package manager yet are urged to download the “deb”, or “rpm” package from the Download center or build LibreOffice from source. Ankush Das 7 min read LibreOffice and OpenOffice are two popular open-source alternatives to Microsoft Office. Inführ also published a video PoC of the attack that shows how to use the event to trigger the execution of a specific function within a Python file.Those who can’t update to the newest version can always disable the macro features in their office suite or avoid trusting any documents that contain macros. “For the solution I looked into the python parsing code a little more in depth and discovered that it is not only possible to specify the function you want to call inside a python script, but it is possible to pass parameters as well (this feature seems to be introduced in the 6.1.x branch) “ “The idea was to abuse the path traversal to traverse down into the users Download directory and load the ODT file as a python script (ergo creating a polyglot file, which is a python file + a working ODT file).” wrote the expert. The suite has its own python interpreter and the file accepts arbitrary commands in one of its parameters and executes them through the system’s command line or console. Four researchers from Ruhr University Bochum discovered the bug, which has been assigned the number CVE202141832 for OpenOffice. The expert pointed out that the python file, named “pydoc.py,” is already included in the LibreOffice software. Updates for LibreOffice and OpenOffice have been released to fix a vulnerability that allows an attacker to make documents appear to be signed by a trusted source. Inführ used a specially ODT file containing a white-colored hyperlink (he has used the white color to make it invisible in the document) that has an “ onmouseover” event to execute a local python file. By exploiting the vulnerability it is possible to trigger the automatic execution of a specific python library included in the suite using a hidden onmouseover event. The expert devised an attack that relies on exploiting a directory traversal vulnerability tracked as CVE-2018-16858.
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