Security Experts:

Serious Flaws Found in 7-Zip File Archiver

An update released this week for the open source file archiver 7-Zip patches a couple of serious vulnerabilities discovered by researchers of Cisco’s Talos group.

7-Zip, which is known for its high compression ratio and ability to handle a large number of archive formats, is used in many products, including antivirus software and security appliances. However, some developers might not be aware that they are using the vulnerable library.

According to Cisco, 7-Zip is plagued by a couple of serious vulnerabilities caused by the lack of proper data input validation.

One of the flaws, tracked as CVE-2016-2335, is related to the way 7-Zip handles Universal Disk Format (UDF) files. An attacker can use a specially crafted file to trigger an out-of-bounds read that can cause a denial-of-service (DoS) condition. In some circumstances, an attacker might also be able to exploit the vulnerability to execute arbitrary code. 

The second vulnerability, identified as CVE-2016-2334, is a heap overflow related to the handling of Zlib files. Cisco said an attacker can exploit this weakness for arbitrary code execution.

Cisco reported the vulnerabilities to 7-Zip developer Igor Pavlov on March 3. The issues were patched on Tuesday with the release of 7-Zip 16.00.

“Sadly, many security vulnerabilities arise from applications which fail to properly validate their input data. Both of these 7-Zip vulnerabilities resulted from flawed input validation,” explained Cisco’s Jaeson Schultz. “Because data can come from a potentially untrusted source, data input validation is of critical importance to all applications’ security.”

7-Zip is not the only open source compression tool analyzed by Cisco researchers. In March, Talos published advisories describing an arbitrary code execution vulnerability affecting the Lhasa library.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.