cbcvebase.
CVE-2020-3153
published 2020-02-19

CVE-2020-3153: A vulnerability in the installer component of Cisco AnyConnect Secure Mobility Client for Windows could allow an authenticated local attacker to copy…

PriorityP184medium6.5CVSS 3.1
AVLACLPRLUINSCCNIHAN
KEVITWEXPLOITRansomware
CISA Known Exploited Vulnerabilitydue 2022-11-14
Exploited in the wild
EPSS
28.31%
97.9th percentile
A vulnerability in the installer component of Cisco AnyConnect Secure Mobility Client for Windows could allow an authenticated local attacker to copy user-supplied files to system level directories with system level privileges. The vulnerability is due to the incorrect handling of directory paths. An attacker could exploit this vulnerability by creating a malicious file and copying the file to a system directory. An exploit could allow the attacker to copy malicious files to arbitrary locations with system level privileges. This could include DLL pre-loading, DLL hijacking, and other related attacks. To exploit this vulnerability, the attacker needs valid credentials on the Windows system.

Affected

3 ranges
VendorProductVersion rangeFixed in
ciscoanyconnect_secure_mobility
ciscoanyconnect_secure_mobility_client< 4.8.020424.8.02042
ciscocisco_anyconnect_secure_mobility_client>= unspecified < n/an/a

Detection & IOCsextracted from sources · hover to see the quote

port62522
filenamevpndownloader.exe
filenamedbghelp.dll
snort
alert tcp any any -> any 62522 (msg:"ET EXPLOIT Cisco AnyConnect Path Traversal Priv Esc (CVE-2020-3153)"; flow:established,to_server; content:"OCSC"; depth:4; content:"vpndownloader.exe"; distance:0; content:"|5c 2e 2e 2f|dbghelp.dll"; fast_pattern; distance:0; reference:url,ssd-disclosure.com/ssd-advisory-cisco-anyconnect-privilege-elevation-through-path-traversal; reference:url,gist.github.com/ykoster/aeaa893d68adbc5004aa873b3290acd1; reference:cve,2020-3153; classtype:attempted-admin; sid:2030280; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, created_at 2020_06_10, cve CVE_2020_3153, deployment Perimeter, deployment Internal, confidence High, signature_severity Major, tag CISA_KEV, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_06_10, mitre_tactic_id TA0007, mitre_tactic_name Discovery, mitre_technique_id T1083, mitre_technique_name File_And_Directory_Discovery; target:dest_ip;)
bytes
OCSC (at depth:4 of TCP payload to port 62522)
bytes
|5c 2e 2e 2f| (backslash + ../ path traversal sequence in IPC payload)
  • Monitor TCP traffic to port 62522 on the loopback interface (Cisco AnyConnect Secure Mobility Agent IPC port). Exploit traffic begins with the 4-byte magic 'OCSC', followed by 'vpndownloader.exe' and a path-traversal sequence (\../) targeting dbghelp.dll.
  • Alert on creation of dbghelp.dll in non-standard or user-writable directories, especially in paths co-located with vpndownloader.exe, as this is the DLL hijacking payload dropped by the exploit.
  • Detect vpndownloader.exe being launched from unexpected or user-writable directories (outside its normal install path), which indicates the installer component has been redirected via path traversal.
  • Check Point IPS signature 'Cisco AnyConnect Secure Mobility Client Privilege Escalation (CVE-2020-3153)' can be used for network-level detection.
  • ·CVE-2020-3153 affects Cisco AnyConnect Secure Mobility Client for Windows versions prior to 4.8.02042 only. Versions 4.8.02042 and later are patched.
  • ·Exploitation requires valid (authenticated) local credentials on the Windows system — this is a local privilege escalation, not a remote unauthenticated attack.
  • ·The Metasploit exploit was successfully tested against AnyConnect versions 4.5.04029, 4.5.05030, and 4.7.04056 on Windows 10 1909 (x64) and Windows 7 SP1 (x86); detection logic should account for these specific version/OS combinations.

CVSS provenance

nvdv3.16.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N
nvdv3.06.5MEDIUMCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N
nvdv2.04.9MEDIUMAV:L/AC:L/Au:N/C:N/I:C/A:N
vulncheck6.5MEDIUM
cisa6.5MEDIUM
vendor_cisco6.5MEDIUM
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