CVE-2017-6542
published 2017-03-27CVE-2017-6542: The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol…
PriorityP267critical9.8CVSS 3.0
AVNACLPRNUINSUCHIHAH
EXPLOIT
EPSS
21.82%
97.3th percentile
The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.
Affected
8 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | putty | < putty 0.67-3 (bookworm) | putty 0.67-3 (bookworm) |
| opensuse | leap | — | — |
| opensuse_project | leap | — | — |
| putty | putty | <= 0.67 | — |
| putty | putty | >= 0 < 0.67-3 | 0.67-3 |
| putty | putty | >= 0 < 0.67-3 | 0.67-3 |
| putty | putty | >= 0 < 0.67-3 | 0.67-3 |
| putty | putty | >= 0 < 0.67-3 | 0.67-3 |
Detection & IOCsextracted from sources · hover to see the quote
bytes↗
\xFF\xFF\xFF\xFD\x0B (agent protocol message with overflowing length field 0xFFFFFFFD)
- →Trigger condition: attacker sends an agent protocol message with a 32-bit length field value of 0xFFFFFFFD (or any value that overflows when 4 is added), causing integer overflow in ssh_agent_channel_data and subsequent heap corruption. Monitor for abnormally large length fields (≥ 0xFFFFFFFC) in SSH agent forwarding socket traffic. ↗
- →Exploitation requires SSH agent forwarding to be enabled and the attacker must be able to connect to the Unix-domain socket ($SSH_AUTH_SOCK) representing the forwarded agent connection. Detect unexpected processes connecting to SSH_AUTH_SOCK on the server side. ↗
- →Affected versions: PuTTY 0.67 and earlier (present-in: 0.67). Flag use of PuTTY versions prior to 0.68 in environments with agent forwarding enabled. ↗
- →The vulnerable function is ssh_agent_channel_data. A crash (heap corruption) of PuTTY following agent-forwarded session activity is a strong indicator of exploitation attempt. ↗
- ·SSH agent forwarding must be explicitly enabled by the user (off by default). The vulnerability is not exploitable unless agent forwarding is active. ↗
- ·An attacker who can already reach the forwarded agent socket can also generate signatures with stored private keys regardless of this CVE — existing OS-level protections on SSH_AUTH_SOCK are the primary defense layer. ↗
CVSS provenance
nvdv3.09.8CRITICALCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv2.07.5HIGHAV:N/AC:L/Au:N/C:P/I:P/A:P
osv9.8CRITICAL
vendor_debian9.8CRITICAL
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Debian
CVE-2017-6542: putty - The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers...
vendor_debian·2017·CVSS 9.8
CVE-2017-6542 [CRITICAL] CVE-2017-6542: putty - The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers...
The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.
Scope: local
bookworm: resolved (fixed in 0.67-3)
bullseye: resolved (fixed in 0.67-3)
forky: resolved (fixed in 0.67-3)
sid: resolved (fixed in 0.67-3)
trixie: resolved (fixed in 0.67-3)
GHSA
GHSA-6q3h-v425-7xx2: The ssh_agent_channel_data function in PuTTY before 0
ghsa_unreviewed·2022-05-14
CVE-2017-6542 [CRITICAL] CWE-119 GHSA-6q3h-v425-7xx2: The ssh_agent_channel_data function in PuTTY before 0
The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.
OSV
CVE-2017-6542: The ssh_agent_channel_data function in PuTTY before 0
osv·2017-03-27·CVSS 9.8
CVE-2017-6542 [CRITICAL] CVE-2017-6542: The ssh_agent_channel_data function in PuTTY before 0
The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have unspecified impact via a large length value in an agent protocol message and leveraging the ability to connect to the Unix-domain socket representing the forwarded agent connection, which trigger a buffer overflow.
No detection rules found.
Bugzilla
CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data
bugzilla·2017-03-13·CVSS 9.8
CVE-2017-6542 [CRITICAL] CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data
CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data
It was found that putty is vulnerable to an integer overflow. An attacker could overwrite the heap data with his own if the system has SSH agent forwarding and he is able to connect to the Unix-domain socket representing the forwarded agent connection.
Upstream patch:
https://git.tartarus.org/?p=simon/putty.git;a=commitdiff;h=4ff22863d895cb7ebfced4cf923a012a614adaa8
References:
http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-agent-fwd-overflow.html
Discussion:
Created putty tracking bugs for this issue:
Affects: epel-5 [bug 1431718]
Affects: epel-6 [bug 1431719]
Affects: fedora-all [bug 1431720]
---
This CVE Bugzilla entry is for community support informational purposes only as it does not affect
Bugzilla
CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data [epel-6]
bugzilla·2017-03-13·CVSS 9.8
CVE-2017-6542 [CRITICAL] CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data [epel-6]
CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data [epel-6]
This is an automatically created tracking bug! It was created to ensure
that one or more security vulnerabilities are fixed in affected versions
of epel-6.
For comments that are specific to the vulnerability please use bugs filed
against the "Security Response" product referenced in the "Blocks" field.
For more information see:
http://fedoraproject.org/wiki/Security/TrackingBugs
When submitting as an update, use the fedpkg template provided in the next
comment(s). This will include the bug IDs of this tracking bug as well as
the relevant top-level CVE bugs.
Please also mention the CVE IDs being fixed in the RPM changelog and the
fedpkg commit message.
Discussion:
Use the following template to for the 'fedpk
Bugzilla
CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data [fedora-all]
bugzilla·2017-03-13·CVSS 9.8
CVE-2017-6542 [CRITICAL] CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data [fedora-all]
CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data [fedora-all]
This is an automatically created tracking bug! It was created to ensure
that one or more security vulnerabilities are fixed in affected versions
of fedora-all.
For comments that are specific to the vulnerability please use bugs filed
against the "Security Response" product referenced in the "Blocks" field.
For more information see:
http://fedoraproject.org/wiki/Security/TrackingBugs
When submitting as an update, use the fedpkg template provided in the next
comment(s). This will include the bug IDs of this tracking bug as well as
the relevant top-level CVE bugs.
Please also mention the CVE IDs being fixed in the RPM changelog and the
fedpkg commit message.
NOTE: this issue affects multiple supported versi
Bugzilla
CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data [epel-5]
bugzilla·2017-03-13·CVSS 9.8
CVE-2017-6542 [CRITICAL] CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data [epel-5]
CVE-2017-6542 putty: Integer overflow in the ssh_agent_channel_data [epel-5]
This is an automatically created tracking bug! It was created to ensure
that one or more security vulnerabilities are fixed in affected versions
of epel-5.
For comments that are specific to the vulnerability please use bugs filed
against the "Security Response" product referenced in the "Blocks" field.
For more information see:
http://fedoraproject.org/wiki/Security/TrackingBugs
When submitting as an update, use the fedpkg template provided in the next
comment(s). This will include the bug IDs of this tracking bug as well as
the relevant top-level CVE bugs.
Please also mention the CVE IDs being fixed in the RPM changelog and the
fedpkg commit message.
Discussion:
Use the following template to for the 'fedpk
http://lists.opensuse.org/opensuse-updates/2017-03/msg00055.htmlhttp://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-agent-fwd-overflow.htmlhttp://www.securityfocus.com/bid/97156http://www.securitytracker.com/id/1038067https://git.tartarus.org/?p=simon/putty.git%3Ba=commitdiff%3Bh=4ff22863d895cb7ebfced4cf923a012a614adaa8https://security.gentoo.org/glsa/201703-03https://security.gentoo.org/glsa/201706-09https://www.exploit-db.com/exploits/42137/http://lists.opensuse.org/opensuse-updates/2017-03/msg00055.htmlhttp://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-agent-fwd-overflow.htmlhttp://www.securityfocus.com/bid/97156http://www.securitytracker.com/id/1038067https://git.tartarus.org/?p=simon/putty.git%3Ba=commitdiff%3Bh=4ff22863d895cb7ebfced4cf923a012a614adaa8https://security.gentoo.org/glsa/201703-03https://security.gentoo.org/glsa/201706-09https://www.exploit-db.com/exploits/42137/
2017-03-27
Published