Bug 1880358 (CVE-2020-24654) - CVE-2020-24654 ark: crafted TAR archive with symlinks can install files outside the extraction directory
Summary: CVE-2020-24654 ark: crafted TAR archive with symlinks can install files outsi...
Alias: CVE-2020-24654
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1880668
Blocks: 1880374
TreeView+ depends on / blocked
Reported: 2020-09-18 10:50 UTC by Dhananjay Arunesh
Modified: 2021-11-02 17:48 UTC (History)
4 users (show)

Fixed In Version: ark 20.08.1
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Last Closed: 2021-11-02 17:48:21 UTC

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Description Dhananjay Arunesh 2020-09-18 10:50:53 UTC
In KDE Ark before 20.08.1, a crafted TAR archive with symlinks can install files outside the extraction directory, as demonstrated by a write operation to a user's home directory.


Comment 1 Todd Cullum 2020-09-18 22:33:13 UTC
Flaw summary:

Using a symbolic link, it's possible for a malicious archive file to be crafted which allows for the extraction of files into other directories within the same scope. For example, a user who downloads an archive into ~/Downloads/ and subsequently uses ark to extract it, could end up extracting files into /tmp or their home directory. The severity of this flaw is very low because the biggest risk would be destruction of data in the case that e.g. there exists a file ~/some_important_info.txt and the flaw is used to trick a user into overwriting some_important_info.txt when the user believes they are extracting into a different directory. However, in this instance, ark-4.10.5, as shipped with Red Hat Enterprise Linux 7, prompts the user about whether they'd like to overwrite the file. Thus, it requires user interaction to actually perform any compromise of integrity.

This flaw could be used to drop random files on the user's file system in locations that they may not be aware of, but it would have to be combined with other vulnerabilities or security compromises in order for an attacker to do anything serious. The most likely way this could be harmful is if the user was ok with overwriting a file in their current directory, but not a file of the same name in another directory, and inadvertently accepted overwriting not knowing where it was being extracted to.

This is quite a stretch but possible.

Comment 2 Todd Cullum 2020-09-18 22:36:06 UTC

The way to mitigate this flaw is to pay attention to the contents of the archive in ark before extracting, to ensure that there are no improper symlinks, and heed the file overwrite warnings.

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