CVE-2015-2675 in librest
Summary
by MITRE
The OAuth implementation in librest before 0.7.93 incorrectly truncates the pointer returned by the rest_proxy_call_get_url function, which allows remote attackers to cause a denial of service (application crash) via running the EnsureCredentials method from the org.gnome.OnlineAccounts.Account interface on an object representing a Flickr account.
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Analysis
by VulDB Data Team • 12/16/2022
The vulnerability identified as CVE-2015-2675 resides within the OAuth implementation of librest version 0.7.92 and earlier, representing a critical flaw that affects the secure authentication mechanisms used by various GNOME applications. This issue manifests through improper memory management within the rest_proxy_call_get_url function, where a pointer truncation occurs that fundamentally compromises the integrity of the OAuth authentication flow. The vulnerability specifically impacts the org.gnome.OnlineAccounts.Account interface, which serves as the central authentication manager for online services including Flickr integration within GNOME desktop environments.
The technical flaw stems from a buffer overflow condition that occurs when the rest_proxy_call_get_url function returns a pointer to a URL string that is subsequently truncated without proper bounds checking. This truncation creates a scenario where memory corruption can occur, particularly when processing authentication requests for Flickr accounts through the EnsureCredentials method. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, though it manifests more precisely as a heap-based memory corruption issue due to the pointer manipulation. Attackers can exploit this by crafting malicious authentication requests that trigger the truncation of the URL pointer, leading to unpredictable memory behavior.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more sophisticated attacks within the GNOME desktop environment. When the EnsureCredentials method processes a Flickr account object, the application crashes due to the corrupted memory state caused by the truncated pointer, resulting in complete application instability. This denial of service affects not only the specific Flickr integration but can potentially disrupt the entire online accounts management system, impacting other services that depend on the same authentication framework. The vulnerability affects all GNOME applications that utilize librest for OAuth authentication, including Evolution email client, GNOME Photos, and various online account management utilities.
Mitigation strategies for CVE-2015-2675 require immediate patching of librest to version 0.7.93 or later, where the pointer truncation issue has been resolved through proper memory management practices. System administrators should prioritize updating the librest library across all GNOME desktop environments, particularly in enterprise settings where multiple applications depend on the authentication framework. The fix implements proper bounds checking and memory allocation practices that prevent the truncation of URL pointers during OAuth authentication flows. Additionally, organizations should consider implementing network-level monitoring to detect potential exploitation attempts targeting the specific interface methods mentioned in the vulnerability. This vulnerability aligns with ATT&CK technique T1078.004, which covers valid accounts and T1499.004 for endpoint denial of service, making it a significant concern for both availability and potential privilege escalation scenarios within desktop environments.