VDB-83258 · CVE-2016-2109 · Nessus 91033

OpenSSL 1.0.1s/1.0.2g ASN.1 BIO crypto/asn1/a_d2i_fp.c d2i_CMS_bio resource management

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.5	$0-$5k	0.00

Summaryinfo

A vulnerability classified as problematic was found in OpenSSL 1.0.1s/1.0.2g. Affected is the function d2i_CMS_bio of the file crypto/asn1/a_d2i_fp.c of the component ASN.1 BIO. Such manipulation leads to resource management. This vulnerability is listed as CVE-2016-2109. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in OpenSSL 1.0.1s/1.0.2g (Network Encryption Software). It has been rated as critical. Affected by this issue is the function d2i_CMS_bio of the file crypto/asn1/a_d2i_fp.c of the component ASN.1 BIO. The manipulation with an unknown input leads to a resource management vulnerability. Using CWE to declare the problem leads to CWE-399. Impacted is confidentiality, integrity, and availability. CVE summarizes:

The asn1_d2i_read_bio function in crypto/asn1/a_d2i_fp.c in the ASN.1 BIO implementation in OpenSSL before 1.0.1t and 1.0.2 before 1.0.2h allows remote attackers to cause a denial of service (memory consumption) via a short invalid encoding.

The weakness was presented 05/03/2016 by Brian Carpenter with Oracle as 20160503.txt as confirmed advisory (Website). The advisory is available at openssl.org. The public release was coordinated in cooperation with the vendor. This vulnerability is handled as CVE-2016-2109 since 01/29/2016. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. The following code is the reason for this vulnerability:

if (!BUF_MEM_grow_clean(b, len + want)) {
   ASN1err(ASN1_F_ASN1_D2I_READ_BIO, ERR_R_MALLOC_FAILURE);
   goto err;
}

while (want > 0) {
   i = BIO_read(in, &(b->data[len]), want);
   if (i <= 0) {
      ASN1err(ASN1_F_ASN1_D2I_READ_BIO,
              ASN1_R_NOT_ENOUGH_DATA);

      goto err;
   }

   len += i;
   want -= i;
}

The advisory points out:

When ASN.1 data is read from a BIO using functions such as d2i_CMS_bio() a short invalid encoding can casuse allocation of large amounts of memory potentially consuming excessive resources or exhausting memory.

The vulnerability was handled as a non-public zero-day exploit for at least 29 days. During that time the estimated underground price was around $5k-$25k. The vulnerability scanner Nessus provides a plugin with the ID 91033 (RHEL 7 : openssl (RHSA-2016:0722)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Red Hat Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 196457 (Ubuntu Security Notification for Openssl Vulnerabilities (USN-2959-1)).

Upgrading to version 1.0.1t or 1.0.2h eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at git.openssl.org. The best possible mitigation is suggested to be upgrading to the latest version. A possible mitigation has been published immediately after the disclosure of the vulnerability. The vulnerability will be addressed with the following lines of code:

size_t chunk_max = ASN1_CHUNK_INITIAL_SIZE;

while (want > 0) {
   size_t chunk = want > chunk_max ? chunk_max : want;

   if (!BUF_MEM_grow_clean(b, len + chunk)) {
      ASN1err(ASN1_F_ASN1_D2I_READ_BIO, ERR_R_MALLOC_FAILURE);
      goto err;
   }
   want -= chunk;
   while (chunk > 0) {
      i = BIO_read(in, &(b->data[len]), chunk);
      if (i <= 0) {
         ASN1err(ASN1_F_ASN1_D2I_READ_BIO,
                 ASN1_R_NOT_ENOUGH_DATA);
         goto err;
      }

      len += i;
      chunk -= i;
   }
   if (chunk_max < INT_MAX/2)
       chunk_max *= 2;
}

The advisory contains the following remark:

The memory based functions such as d2i_X509() are *not* affected. Since the memory based functions are used by the TLS library, TLS applications are not affected.

The vulnerability is also documented in the databases at Tenable (91033) and SecurityFocus (BID 91787†). tools.cisco.com is providing further details. See VDB-76354, VDB-78584, VDB-78603 and VDB-78601 for similar entries. If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

Network Encryption Software

Name

OpenSSL

Version

License

open-source

Support

end of life (old version)

Website

Product: https://www.openssl.org/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.7
VulDB Meta Temp Score: 8.5

VulDB Base Score: 9.8
VulDB Temp Score: 9.4
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

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

NVD Base Score: 🔍

Exploitinginfo

Class: Resource management
CWE: CWE-399 / CWE-404
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 91033
Nessus Name: RHEL 7 : openssl (RHSA-2016:0722)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 841567
OpenVAS Name: SuSE Update for openssl openSUSE-SU-2016:1240-1 (openssl)
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

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

Upgrade: OpenSSL 1.0.1t/1.0.2h
Patch: c62981390d6cf9e3d612c489b8b77c2913b25807

Timelineinfo

01/29/2016 🔍
04/04/2016 +66 days 🔍
05/03/2016 +29 days 🔍
05/03/2016 +0 days 🔍
05/04/2016 +1 days 🔍
05/04/2016 +0 days 🔍
05/11/2016 +7 days 🔍
07/15/2016 +65 days 🔍
07/28/2022 +2204 days 🔍

Sourcesinfo

Product: openssl.org

Advisory: 20160503.txt
Researcher: Brian Carpenter
Organization: Oracle
Status: Confirmed
Confirmation: 🔍
Coordinated: 🔍

CVE: CVE-2016-2109 (🔍)
GCVE (CVE): GCVE-0-2016-2109
GCVE (VulDB): GCVE-100-83258

OVAL: 🔍

SecurityFocus: 91787 - Oracle July 2016 Critical Patch Update Multiple Vulnerabilities
SecurityTracker: 1035721

Misc.: 🔍
See also: 🔍

Entryinfo

Created: 05/04/2016 11:34
Updated: 07/28/2022 08:05
Changes: 05/04/2016 11:34 (83), 11/12/2018 08:32 (14), 07/28/2022 08:05 (4)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.