CVE-2019-1010177 in Jsish
Summary
by MITRE
Jsish 2.4.70 2.047 is affected by: Use After Free. The impact is: denial of service and possibly arbitrary code execution. The component is: function Jsi_RegExpNew (jsi/jsiRegexp.c:39). The attack vector is: executing crafted javascript code. The fixed version is: after commit 48a66c798d.
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Analysis
by VulDB Data Team • 07/12/2020
The vulnerability identified as CVE-2019-1010177 affects Jsish version 2.4.70 and 2.047, representing a critical use after free condition that can lead to denial of service and potential arbitrary code execution. This flaw exists within the Jsi_RegExpNew function located in jsi/jsiRegexp.c at line 39, making it a significant security concern for systems utilizing this JavaScript interpreter. The vulnerability stems from improper memory management where freed memory is accessed after it has been deallocated, creating opportunities for malicious actors to exploit the system through carefully crafted javascript code execution.
The technical implementation of this vulnerability involves the function Jsi_RegExpNew which handles regular expression creation and management within the Jsish interpreter. When processing specific javascript inputs that trigger regular expression operations, the function fails to properly manage memory allocation and deallocation sequences. This use after free condition occurs when the interpreter allocates memory for regular expression objects and subsequently frees it, but continues to reference or operate on the freed memory location. Such memory corruption can result in unpredictable behavior including program crashes, denial of service conditions, or more critically, execution of arbitrary code when attackers can control the memory layout and overwrite critical function pointers or return addresses.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as the use after free condition creates opportunities for privilege escalation and code execution attacks. Attackers can craft javascript payloads that specifically target the memory management patterns within Jsi_RegExpNew to trigger the vulnerable code path. The attack vector requires executing crafted javascript code against a system running the vulnerable Jsish interpreter, making web applications and server-side javascript environments particularly susceptible. This vulnerability aligns with CWE-416, which specifically addresses use after free conditions, and represents a classic memory safety issue that can be exploited through the ATT&CK technique of code injection and memory corruption attacks.
Mitigation strategies for this vulnerability require immediate patching of the Jsish interpreter to version containing the fix implemented after commit 48a66c798d. Organizations should prioritize updating their Jsish installations and conducting thorough security assessments of systems running vulnerable versions. Additional protective measures include implementing input validation and sanitization for all javascript code execution paths, deploying runtime application self-protection mechanisms, and establishing monitoring protocols to detect anomalous memory access patterns. The fix implemented in the subsequent commit addresses the core memory management issue by ensuring proper deallocation and nullification of pointers after memory release, preventing the reuse of freed memory segments that could be exploited by malicious javascript payloads. Security teams should also consider implementing sandboxing techniques and restricting javascript execution privileges to minimize potential impact if exploitation occurs.