Security Experts:

Backdoor Disguised as Typo Fix Added to PHP Source Code

The developers of the PHP scripting language revealed on Sunday that they had identified what appeared to be malicious code in the php-src repository hosted on the server.

The unauthorized code was disguised as two typo fix-related commits apparently pushed by Rasmus Lerdorf, author of the PHP language, and Nikita Popov, an important PHP contributor. The code seems to allow an attacker to remotely execute arbitrary PHP code.

The investigation into this incident is ongoing, but the backdoor was discovered quickly and it apparently did not make it into a PHP update made available to users.

“We don't yet know how exactly this happened, but everything points towards a compromise of the server (rather than a compromise of an individual git account),” Popov explained after the incident was discovered.

“While investigation is still underway, we have decided that maintaining our own git infrastructure is an unnecessary security risk, and that we will discontinue the server. Instead, the repositories on GitHub, which were previously only mirrors, will become canonical. This means that changes should be pushed directly to GitHub rather than to,” he added.

Interestingly, the malicious code is triggered by the string “zerodium.” Zerodium is the name of a well-known and controversial exploit acquisition company that claims to provide exploits to “government organizations (mainly from Europe and North America) in need of advanced zero-day exploits and cybersecurity capabilities.”

The commit added to the PHP code also contains the text “REMOVETHIS: sold to zerodium, mid 2017.”

Backdoor added to PHP source code

It’s unclear if and how Zerodium is linked to this incident, but SecurityWeek has reached out to the company for comment and will update this article if it responds.

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Related: Critical Vulnerability Patched in PHP Package Repository

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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.