7-zip vulnerability gives hackers the keys to the kingdom

A threat actor could abuse the popular archiving app (opens in new tab), 7-zip and gain elevated privileges on a device to which they already have access.

A GitHub user going by the name Kagancapar discovered a zero-day vulnerability in 7-zip for the Windows operating system (OS). The findings, posted on GitHub, revealed that, "Windows allows privilege escalation and command execution when a file with the .7z extension is dragged to the Help>Contents area."

Here’s how it works: a threat actor crafts a malicious file, and gives it a .7z extension (the one that an archive compressed with 7-zip can have). They then need to drag and drop that file onto the 7-zip help window, and run a command in admin mode.

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Waiting for a patch

After that, they’ll get elevated privileges on the target endpoint, allowing them to run more complex commands and run different apps. More details can be found in this proof-of-concept video (opens in new tab).

The vulnerability is now tracked as CVE-2022-29072. The latest 7-zip version is 21.07, released in late December last year, which means the zero-day was not yet patched. 

Those worried about potentially being targeted through 7-zip can protect their virtual premises by deleting the 7-zip.chm file, Tom’s Hardware reported. Another method is to grant 7-zip only read and run permissions for all users. 

The file compression (opens in new tab) company doesn’t seem to have commented on the vulnerability much, other than refusing to take responsibility for the flaw, given that it depends on Microsoft Help in Windows. However, as Kagancapar explained, dropping the malicious file on the Help window triggers a heap overflow in 7zFM.exe, which leads to the escalation of privilege, arguing that for this reason alone - it’s 7-zip who should be addressing the issue.

7-zip is one of the three most popular file (opens in new tab) archiving applications, whose popularity is only rivaled by giants WinZIP and WinRaR. 

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Via: Tom's Hardware (opens in new tab)