Bug 1841199 (CVE-2020-13398)
| Summary: | CVE-2020-13398 freerdp: Out-of-bounds write in crypto_rsa_common in libfreerdp/crypto/crypto.c | ||
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| Product: | [Other] Security Response | Reporter: | Michael Kaplan <mkaplan> |
| Component: | vulnerability | Assignee: | Red Hat Product Security <security-response-team> |
| Status: | CLOSED ERRATA | QA Contact: | |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | unspecified | CC: | mads, negativo17, oholy, pahan, yozone |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | freerdp 2.1.1 | Doc Type: | If docs needed, set a value |
| Doc Text: |
An issue was found in freerdp's libfreerdp/crypto/crypto.c, in versions before 2.1.1, where buffer access with an incorrect length value, leads to an out-of-bounds write. This flaw allows a remote, unauthenticated, attacker running an RDP server, or a local attacker, using a specially crafted certificate, to cause an out-of-bounds write into client process memory, corrupting the integrity of the data used in the RSA encryption functionality, or causing a denial of service.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | 2020-06-04 23:20:35 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | 1841200, 1841201, 1841974, 1841975, 1841976, 1841977, 1841978, 1841979, 1841980 | ||
| Bug Blocks: | 1841202 | ||
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Description
Michael Kaplan
2020-05-28 15:48:35 UTC
Created freerdp tracking bugs for this issue: Affects: epel-all [bug 1841200] Affects: fedora-all [bug 1841201] Technical Summary:
The vulnerable function's signature is:
static int crypto_rsa_common(const BYTE* input, int length, UINT32 key_length, const BYTE* modulus,
const BYTE* exponent, int exponent_size, BYTE* output)
There was a call to malloc: input_reverse = (BYTE*)malloc(2 * key_length + exponent_size) and subsequently, a call to: memcpy(input_reverse, input, length). It was possible for length to be unequal to the allocated memory size of 2 * key_length + exponent_size, which could cause a heap buffer overflow in the memory pointed to by input_reverse. The patch ensures that the length cannot be longer than the allocation size, initializes the allocated memory to zero using calloc, and performs several other length checks.
The vulnerable crypto_rsa_common() is used by both crypto_rsa_public_encrypt() and crypto_rsa_public_decrypt(). However, the input value to the system which could be used for exploitation appears to be only locally modifiable. There are other values used in the computation which could be remotely modifiable. Mitigation: To mitigate this flaw, only make connection attempts to trusted RDP servers from the RDP client application. This issue has been addressed in the following products: Red Hat Enterprise Linux 6 Via RHSA-2020:2406 https://access.redhat.com/errata/RHSA-2020:2406 This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2020:2407 https://access.redhat.com/errata/RHSA-2020:2407 This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2020-13398 This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2020:2405 https://access.redhat.com/errata/RHSA-2020:2405 This issue has been addressed in the following products: Red Hat Enterprise Linux 8.0 Update Services for SAP Solutions Via RHSA-2020:2417 https://access.redhat.com/errata/RHSA-2020:2417 This issue has been addressed in the following products: Red Hat Enterprise Linux 8.1 Extended Update Support Via RHSA-2020:2415 https://access.redhat.com/errata/RHSA-2020:2415 |