Some Web apps written in PHP call a vulnerable glibc function, potentially opening the door to attacks A critical vulnerability in glibc, a core Linux library, can be exploited remotely through WordPress and likely other PHP applications to compromise Web servers. The buffer overflow vulnerability, dubbed Ghost, was reported Tuesday by researchers from security vendor Qualys. It is identified as CVE-2015-0235 in the Common Vulnerabilities and Exposures database. The bug is located in the gethostbyname*() functions of the glibc (GNU C Library) version 2.17 and older. It was fixed in glibc-2.18, released in May 2013, but it wasn’t flagged as a security vulnerability at the time. As a result, some Linux distributions, especially those developed for long-term support, did not backport the patch and were still using vulnerable glibc versions when the Qualys researchers identified the security implications of the bug during a code audit. Exploiting the vulnerability for remote code execution also depends on other factors, like whether the targeted application uses the glibc gethostbyname*() functions and in what context. Researchers identified that clockdiff, procmail, pppd and the Exim mail server software could be used as attack vectors to some extent. However, researchers from website security research firm Sucuri said Wednesday that they have good reasons to believe the flaw can also be exploited through Web applications written in PHP that use gethostbyname() function wrappers. This has the potentially to significantly expand the attack vectors. One clear example of such a PHP application is WordPress, which uses a function called wp_http_validate_url() to validate the URLs of pingback posts. “It does so by using gethostbyname(), so an attacker could leverage this vector to insert a malicious URL that would trigger a buffer overflow bug, server-side, potentially allowing him to gain privileges on the server,” Sucuri senior vulnerability researcher Marc-Alexandre Montpas said in a blog post. In a comment to Montpas’s blog post, HD Moore, chief research officer at Rapid7 and main developer of the Metasploit penetration testing tool, posted a PHP command that can be used to check if a Web server is vulnerable. Then Thursday, security researchers from Trustwave SpiderLabs created a proof-of-concept script to trigger the glibc buffer overflow though the WordPress pingback feature. “This PoC allows users to remotely verify if a target web server is vulnerable to the CVE however it does not demonstrate exploitability,” they said in a blog post. Nevertheless, WordPress users are advised to disable the XML-RPC process completely or to block pingback requests. Server administrators are advised to update their versions of glibc as soon as possible. Debian 7 (wheezy), Red Hat Enterprise Linux 6 and 7, CentOS 6 and 7 and Ubuntu 12.04 were among the Linux distributions identified as vulnerable and which have since released patches. “When attackers are attempting to exploit this vulnerability against your web servers, there will most likely be error messages (segmentation faults, etc…) that will indicate a problem,” the Trustwave researchers said. “Organizations should be vigilant in monitoring their logs and following up on an anomalous errors.” Related content feature Windows 11 Insider Previews: What’s in the latest build? Get the latest info on new preview builds of Windows 11 as they roll out to Windows Insiders. Now updated for Build 22635.3566 for the Beta Channel, released on April 26, 2024. By Preston Gralla Apr 26, 2024 251 mins Small and Medium Business Microsoft Windows 11 news Dropbox adds end-to-end encryption for team folders Dropbox this week unveiled a range of features, including security updates and key management, and the ability to co-edit Microsoft 365 documents from within the file-sharing app. By Matthew Finnegan Apr 26, 2024 3 mins Cloud Storage Collaboration Software Productivity Software feature Android versions: A living history from 1.0 to 15 Explore Android's ongoing evolution with this visual timeline of versions, starting B.C. (Before Cupcake) and going all the way to 2024's Android 15 (beta) release. By JR Raphael Apr 26, 2024 23 mins Small and Medium Business Smartphones Android news analysis The unspoken obnoxiousness of Google's Gemini improvements Google's Gemini chatbot is seeing all sorts of upgrades on Android this week, but those advancements reveal a darker underlying reality. By JR Raphael Apr 26, 2024 12 mins Google Assistant Google Android Podcasts Videos Resources Events SUBSCRIBE TO OUR NEWSLETTER From our editors straight to your inbox Get started by entering your email address below. Please enter a valid email address Subscribe