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CISA: Second SharePoint Flaw Disclosed at Pwn2Own Exploited in Attacks

CISA says a second SharePoint vulnerability demonstrated last year at Pwn2Own, CVE-2023-24955, has been exploited in the wild.

CISA known exploited vulnerabilites

The US cybersecurity agency CISA on Tuesday added a second SharePoint flaw demonstrated last year at a Pwn2Own hacking competition to its Known Exploited Vulnerabilities (KEV) list.

The flaw, tracked as CVE-2023-24955, was demonstrated by the Star Labs team in March 2023 at Pwn2Own Vancouver alongside CVE-2023-29357. This two-bug exploit chain, which allows unauthenticated remote code execution on SharePoint servers with elevated privileges, earned the Star Labs team $100,000 at Pwn2Own. 

CVE-2023-24955 and CVE-2023-29357 were patched by Microsoft with SharePoint updates released in May and June 2023, respectively. 

The Star Labs researchers disclosed their findings in September and released a PoC exploit in mid-December.

Less than one month later, CISA added CVE-2023-29357 to its KEV catalog. Now, the second vulnerability that is part of the exploit chain, CVE-2023-24955, has also been added to the list.

No information is publicly available on the attacks exploiting these vulnerabilities, which are presumably chained by threat actors. CISA’s entry in the KEV list does reveal that the attacks the agency is aware of do not involve ransomware. 

Microsoft’s advisories for CVE-2023-24955 and CVE-2023-29357 have yet to be updated to inform customers about in-the-wild exploitation, but both have an exploitation assessment of ‘exploitation more likely’. 

CISA’s KEV catalog currently includes four SharePoint vulnerabilities that have been exploited in the wild since 2019. The latest entry, CVE-2023-24955, needs to be addressed by government organizations until April 16.

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Written By

Eduard Kovacs (@EduardKovacs) is a managing 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.


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