cbcvebase.
CVE-2024-12084
published 2025-01-15

CVE-2024-12084: A heap-based buffer overflow flaw was found in the rsync daemon. This issue is due to improper handling of attacker-controlled checksum lengths (s2length) in…

PriorityP275critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
72.06%
99.4th percentile
A heap-based buffer overflow flaw was found in the rsync daemon. This issue is due to improper handling of attacker-controlled checksum lengths (s2length) in the code. When MAX_DIGEST_LEN exceeds the fixed SUM_LENGTH (16 bytes), an attacker can write out of bounds in the sum2 buffer.

Affected

30 ranges· showing 25
VendorProductVersion rangeFixed in
almalinuxalmalinux
debianrsync< rsync 3.2.7-1+deb12u1 (bookworm)rsync 3.2.7-1+deb12u1 (bookworm)
msrcazl3_rsync_3.2.7-1_on_azure_linux_3.0
msrcazl3_rsync_3.4.1-1_on_azure_linux_3.0
msrccbl2_rsync_3.2.5-1_on_cbl_mariner_2.0
msrccbl2_rsync_3.4.1-1_on_cbl_mariner_2.0
nixosnixos< 24.1124.11
nixosnixos
paloaltopan-os
redhatenterprise_linux
sambarsync
sambarsync
sambarsync>= 0 < 3.2.7-1+deb12u13.2.7-1+deb12u1
sambarsync>= 0 < 3.3.0+ds1-33.3.0+ds1-3
sambarsync>= 0 < 3.3.0+ds1-33.3.0+ds1-3
sambarsync>= 0 < 3.1.3-8ubuntu0.93.1.3-8ubuntu0.9
sambarsync>= 0 < 3.1.3-8ubuntu0.83.1.3-8ubuntu0.8
sambarsync>= 0 < 3.2.7-0ubuntu0.22.04.43.2.7-0ubuntu0.22.04.4
sambarsync>= 0 < 3.2.7-0ubuntu0.22.04.33.2.7-0ubuntu0.22.04.3
sambarsync>= 0 < 3.2.7-1ubuntu1.23.2.7-1ubuntu1.2
sambarsync>= 0 < 3.2.7-1ubuntu1.13.2.7-1ubuntu1.1
sambarsync>= 0 < 3.3.0-1ubuntu0.23.3.0-1ubuntu0.2
sambarsync>= 0 < 3.3.0-1ubuntu0.13.3.0-1ubuntu0.1
sambarsync>= 0 < 3.1.0-2ubuntu0.4+esm23.1.0-2ubuntu0.4+esm2
sambarsync>= 0 < 3.1.0-2ubuntu0.4+esm13.1.0-2ubuntu0.4+esm1

Detection & IOCsextracted from sources · hover to see the quote

port873
bytes
|40|RSYNCD|3a|
bytes
|00 00 07|
bytes
|0e|
snort
alert tcp any any -> $HOME_NET 873 (msg:"ET EXPLOIT Samba rsync s2length Checksum Length Heap Buffer Overflow (CVE-2024-12084)"; flow:established,to_server; content:"|40|RSYNCD|3a|"; fast_pattern; content:"--server"; content:"--sender"; content:"|00 00 07|"; content:"|0e|"; distance:0; byte_test:1,&,0x80,0,relative; byte_test:4,>,16,9,relative,little; byte_test:4,<,65,9,relative,little; reference:cve,2024-12084; classtype:attempted-user; sid:2067354; rev:2; metadata:affected_product Samba, attack_target Server, created_at 2026_02_06, cve CVE_2024_12084, deployment Perimeter, deployment Internal, confidence Medium, signature_severity Major, tag Exploit, updated_at 2026_02_17, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application; target:dest_ip;)
  • Exploit traffic targets TCP port 873 (rsync daemon). Look for established connections to the rsync daemon containing the protocol banner |40|RSYNCD|3a| followed by --server and --sender flags, with a checksum length field (s2length) greater than 16 and less than 65 (byte_test:4,>,16,9,relative,little and byte_test:4,<,65,9,relative,little), indicating an attacker-controlled value exceeding SUM_LENGTH (16 bytes).
  • The vulnerability is triggered when MAX_DIGEST_LEN exceeds the fixed SUM_LENGTH (16 bytes), causing an out-of-bounds write in the sum2 buffer. Detection should focus on attacker-controlled s2length values larger than 16 bytes in rsync checksum negotiation.
  • Only rsync versions 3.2.7 and 3.3.0 are affected. Prioritize detection and patching on hosts running these specific versions.
  • Anonymous read access to an rsync daemon (rsyncd) is the highest-risk configuration. Attackers only need anonymous read access to trigger the vulnerability — no credentials required in default rsyncd configurations.
  • The Snort/ET rule uses sid:2067354 rev:2. Monitor IDS/IPS alert logs for this SID firing on perimeter and internal sensors.
  • ·Risk is significantly reduced when rsync is accessed via a remote-shell transport (e.g., SSH) rather than direct TCP to the rsync daemon, because shell authentication restricts the attack surface.
  • ·The default rsyncd configuration does not require authentication; anonymous read access is common on file-sharing/mirroring hosts, making those deployments fully exposed with no available mitigation short of patching.
  • ·Red Hat considers severity Critical only when anonymous read access is allowed; severity may be significantly reduced depending on configuration.

CVSS provenance

nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
osv9.8CRITICAL
vendor_debian9.8CRITICAL
vendor_msrc9.8CRITICAL
vendor_redhat9.8CRITICAL
vendor_ubuntu9.8CRITICAL
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