Linux Kernel up to 4.17.3 POSIX Timer posix-timers.c siginfo::si_overrun integer overflow

CVSS Meta Temp Score
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CTI Interest Score
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5.3$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic was found in Linux Kernel up to 4.17.3. The affected element is the function siginfo::si_overrun of the file kernel/time/posix-timers.c of the component POSIX Timer. Executing a manipulation can lead to integer overflow. This vulnerability appears as CVE-2018-12896. The attack requires local access. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 4.17.3 (Operating System). It has been declared as problematic. This vulnerability affects the function siginfo::si_overrun of the file kernel/time/posix-timers.c of the component POSIX Timer. The manipulation with an unknown input leads to a integer overflow vulnerability. The CWE definition for the vulnerability is CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

An issue was discovered in the Linux kernel through 4.17.3. An Integer Overflow in kernel/time/posix-timers.c in the POSIX timer code is caused by the way the overrun accounting works. Depending on interval and expiry time values, the overrun can be larger than INT_MAX, but the accounting is int based. This basically makes the accounting values, which are visible to user space via timer_getoverrun(2) and siginfo::si_overrun, random. For example, a local user can cause a denial of service (signed integer overflow) via crafted mmap, futex, timer_create, and timer_settime system calls.

The bug was discovered 06/22/2018. The weakness was presented 07/02/2018 (Website). The advisory is shared for download at bugzilla.kernel.org. This vulnerability was named CVE-2018-12896 since 06/26/2018. The attack needs to be approached locally. The successful exploitation requires a single authentication. There are known technical details, but no exploit is available.

The vulnerability was handled as a non-public zero-day exploit for at least 10 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 111243 (Fedora 27 : kernel (2018-8484550fff)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Fedora Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 157818 (Oracle Enterprise Linux Security Update for Unbreakable Enterprise kernel (ELSA-2018-4242)).

Upgrading eliminates this vulnerability. A possible mitigation has been published 2 weeks after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (111243) and SecurityFocus (BID 107127†). See VDB-115041, VDB-119428, VDB-120200 and VDB-120201 for similar entries. Once again VulDB remains the best source for vulnerability data.

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔍

CVSSv2info

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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Integer overflow
CWE: CWE-190 / CWE-189
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: No

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 111243
Nessus Name: Fedora 27 : kernel (2018-8484550fff)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Patch: github.com

Timelineinfo

06/22/2018 🔍
06/26/2018 +4 days 🔍
07/02/2018 +5 days 🔍
07/02/2018 +0 days 🔍
07/03/2018 +1 days 🔍
07/13/2018 +10 days 🔍
07/24/2018 +11 days 🔍
02/15/2019 +206 days 🔍
03/29/2023 +1503 days 🔍

Sourcesinfo

Vendor: kernel.org

Advisory: FEDORA-2018-8484550fff
Status: Confirmed

CVE: CVE-2018-12896 (🔍)
GCVE (CVE): GCVE-0-2018-12896
GCVE (VulDB): GCVE-100-120148
SecurityFocus: 107127 - Linux Kernel CVE-2019-6974 Security Bypass Vulnerability

See also: 🔍

Entryinfo

Created: 07/03/2018 07:50
Updated: 03/29/2023 15:11
Changes: 07/03/2018 07:50 (76), 02/23/2020 16:49 (6), 03/29/2023 15:05 (5), 03/29/2023 15:11 (1)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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