CVE-2015-8778 in C Library
Summary
by MITRE
Integer overflow in the GNU C Library (aka glibc or libc6) before 2.23 allows context-dependent attackers to cause a denial of service (application crash) or possibly execute arbitrary code via the size argument to the __hcreate_r function, which triggers out-of-bounds heap-memory access.
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Analysis
by VulDB Data Team • 07/25/2022
The vulnerability identified as CVE-2015-8778 represents a critical integer overflow flaw within the GNU C Library version 2.22 and earlier, affecting systems that rely on glibc for standard C library functions. This vulnerability specifically targets the __hcreate_r function, which is used for hash table creation in applications utilizing the standard library. The flaw occurs when an attacker provides a malicious size argument that triggers an integer overflow condition, leading to unpredictable behavior in memory allocation and access patterns. According to CWE-190, this vulnerability falls under the category of integer overflow, where an integer value exceeds its maximum representable value and wraps around to a smaller value, creating exploitable conditions.
The technical implementation of this vulnerability exploits the improper handling of integer values during memory allocation operations within the hash table creation process. When the __hcreate_r function processes a specially crafted size argument, the integer overflow causes the system to allocate insufficient heap memory or access memory regions beyond the allocated boundaries. This out-of-bounds memory access can result in application crashes due to segmentation faults or potentially allow attackers to execute arbitrary code through memory corruption techniques. The vulnerability demonstrates characteristics consistent with CWE-787, out-of-bounds write conditions, where the system writes data to memory locations outside the intended buffer boundaries.
From an operational perspective, this vulnerability poses significant risks to systems running affected glibc versions, particularly those that utilize hash table functionality or applications that depend on standard library hash table implementations. Attackers can leverage this flaw to cause denial of service conditions that may disrupt critical services or potentially escalate privileges through code execution. The context-dependent nature of this vulnerability means that exploitation requires specific conditions where the target application invokes the vulnerable __hcreate_r function with malicious input parameters. This characteristic aligns with ATT&CK technique T1203, "Exploitation for Client Execution," which describes how attackers can use application flaws to execute arbitrary code.
The impact of CVE-2015-8778 extends across numerous Linux distributions and Unix-like systems that utilize glibc as their standard C library implementation. Systems running applications such as web servers, database engines, and network services that incorporate hash table functionality are particularly vulnerable. The vulnerability's potential for arbitrary code execution makes it especially dangerous in environments where privilege escalation could lead to complete system compromise. Organizations should prioritize patching affected systems and implementing monitoring for suspicious memory access patterns that might indicate exploitation attempts. The remediation approach involves upgrading to glibc version 2.23 or later, where the integer overflow handling has been corrected to prevent the out-of-bounds memory access conditions that enable this vulnerability.