Avira Free Security Suite File Writes Vulnerability [CVE-2019-11396]

CVE number – CVE-2019-11396

The permissive access rights on the SoftwareUpdater folder (files / folders) are incompatible with the privileged file manipulation performed by the product.

Files can be created that can be used by an unprivileged user to obtain SYSTEM privileges. Arbitrary file creation can be achieved by abusing the SwuConfig.json file creation. An unprivileged user can replace these files by symbolic links to arbitrary files.

When an update occurs, a privileged service creates a file and sets its access rights, offering write access to the Everyone group in any directory.

Affected software – Avira Free Security Suite 2019 – Software Updater v2.0.6.13175

Please update to the latest version in order to fix this issue.

Timeline of disclosure

15/Apr/2019 – Responsible disclosure initiated with the vendor.

16/Apr/2019 – Vendor requested more details about the exploitation.

21/Apr/2019 – CVE assigned (reserved) CVE-2019-11396.

21/Apr/2019 – Email sent to the vendor requesting an update on the fix status.

23/Apr/2019 – The vendor has reproduced the vulnerability and works to correct it.

21/May/2019 – The vulnerability has been fixed and the vendor has informed that the release will be done in one week.

28/May/2019 – The vendor reported that the vulnerability had been fixed and that the update was public.

o4/Jun/2019 – Email sent to the vendor stating that the vulnerability has not been fixed.

18/Jun/2019 – Avira reported that the vulnerability has been fixed.

19/Jun/2019 – Email sent to the vendor stating that the vulnerability has not been fixed.

03/Jul/2019 – Avira replied that he had identified the real problem and was going to try to correct it again.

08/Jul/2019 – The vendor fixed the vulnerability.

Duncan Newell

Duncan is a technology professional with over 20 years experience of working in various IT roles. He has a interest in cyber security, and has a wide range of other skills in radio, electronics and telecommunications.

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